Method for purifying reclaimed polymers

ABSTRACT

A method for purifying a reclaimed polymer is disclosed. In one embodiment, the method involves obtaining reclaimed polymer, contacting the reclaimed polymer with a first fluid solvent to produce an extracted reclaimed polymer; then dissolving the extracted reclaimed polymer in a solvent to produce a first solution comprising polymer. The first solution is settled and then filtered. A purer polymer is separated from the resulting solution.

FIELD OF THE INVENTION

The present invention generally relates to a method for purifyingcontaminated polymers through the use of a pressurized solvent,settling, and/or filtration. More specifically, this invention relatesto a method for purifying recycled polymers, such as post-consumer andpost-industrial recycled plastics, to produce a colorless or clear, odorfree, virgin-like polymer. It is particularly useful for thepurification of polyolefins, such as polyethylene and polypropylene.

BACKGROUND OF THE INVENTION

Polymers, especially synthetic plastics, are ubiquitous in daily lifedue to their relatively low production costs and good balance ofmaterial properties. Synthetic plastics are used in a wide variety ofapplications, such as packaging, automotive components, medical devices,and consumer goods. To meet the high demand of these applications, tensof billions of pounds of synthetic plastics are produced globally on anannual basis. The overwhelming majority of synthetic plastics areproduced from increasingly scarce fossil sources, such as petroleum andnatural gas. Additionally, the manufacturing of synthetic plastics fromfossil sources produces CO₂ as a by-product.

The ubiquitous use of synthetic plastics has consequently resulted inmillions of tons of plastic waste being generated every year. While themajority of plastic waste is landfilled via municipal solid wasteprograms, a significant portion of plastic waste is found in theenvironment as litter, which is unsightly and potentially harmful toecosystems. Plastic waste is often washed into river systems andultimately out to sea.

Plastics recycling has emerged as one solution to mitigate the issuesassociated with the wide-spread usage of plastics. Recovering andre-using plastics diverts waste from landfills and reduces the demandfor virgin plastics made from fossil-based resources, which consequentlyreduces greenhouse gas emissions. In developed regions, such as theUnited States and the European Union, rates of plastics recycling areincreasing due to greater awareness by consumers, businesses, andindustrial manufacturing operations. The majority of recycled materials,including plastics, are mixed into a single stream which is collectedand processed by a material recovery facility (MRF). At the MRF,materials are sorted, washed, and packaged for resale. Plastics can besorted into individual materials, such as high-density polyethylene(HDPE) or poly(ethylene terephthalate) (PET), or mixed streams of othercommon plastics, such as polypropylene (PP), low-density polyethylene(LDPE), poly(vinyl chloride) (PVC), polystyrene (PS), polycarbonate(PC), and polyamides (PA). The single or mixed streams can then befurther sorted, washed, and reprocessed into a pellet that is suitablefor re-use in plastics processing, for example blow and injectionmolding.

Though recycled plastics are sorted into predominately uniform streamsand are washed with aqueous and/or caustic solutions, the finalreprocessed pellet often remains highly contaminated with unwanted wasteimpurities, such as spoiled food residue and residual perfumecomponents. In addition, recycled plastic pellets, except for those fromrecycled beverage containers, are darkly colored due to the mixture ofdyes and pigments commonly used to colorize plastic articles. Whilethere are some applications that are insensitive to color andcontamination (for example black plastic paint containers and concealedautomotive components), the majority of applications require non-coloredpellets. The need for high quality, “virgin-like” recycled resin isespecially important for food and drug contact applications, such asfood packaging. In addition to being contaminated with impurities andmixed colorants, many recycled resin products are often heterogeneous inchemical composition and may contain a significant amount of polymericcontamination, such as polyethylene (PE) contamination in recycled PPand vice versa.

Mechanical recycling, also known as secondary recycling, is the processof converting recycled plastic waste into a re-usable form forsubsequent manufacturing. A more detailed review of mechanical recyclingand other plastics recovery processes are described in S. M. Al-Salem,P. Lettieri, J. Baeyens, “Recycling and recovery routes of plastic solidwaste (PSW): A review”, Waste Management, Volume 29, Issue 10, October2009, Pages 2625-2643, ISSN 0956-053X. While advances in mechanicalrecycling technology have improved the quality of recycled polymers tosome degree, there are fundamental limitations of mechanicaldecontamination approaches, such as the physical entrapment of pigmentswithin a polymer matrix. Thus, even with the improvements in mechanicalrecycling technology, the dark color and high levels of chemicalcontamination in currently available recycled plastic waste preventsbroader usage of recycled resins by the plastics industry.

To overcome the fundamental limitations of mechanical recycling, therehave been many methods developed to purify contaminated polymers viachemical approaches, or chemical recycling. Most of these methods usesolvents to decontaminate and purify polymers. The use of solventsenables the extraction of impurities and the dissolution of polymers,which further enables alternative separation technologies.

For example, U.S. Pat. No. 7,935,736 describes a method for recyclingpolyester from polyester-containing waste using a solvent to dissolvethe polyester prior to cleaning. The '736 patent also describes the needto use a precipitant to recover the polyester from the solvent.

In another example, U.S. Pat. No. 6,555,588 describes a method toproduce a polypropylene blend from a plastic mixture comprised of otherpolymers. The '588 patent describes the extraction of contaminants froma polymer at a temperature below the dissolution temperature of thepolymer in the selected solvent, such as hexane, for a specifiedresidence period. The '588 patent further describes increasing thetemperature of the solvent (or a second solvent) to dissolve the polymerprior to filtration. The '588 patent yet further describes the use ofshearing or flow to precipitate polypropylene from solution. Thepolypropylene blend described in the '588 patent contained polyethylenecontamination up to 5.6 wt %.

In another example, European Patent Application No. 849,312 (translatedfrom German to English) describes a process to obtain purifiedpolyolefins from a polyolefin-containing plastic mixture or apolyolefin-containing waste. The '312 patent application describes theextraction of polyolefin mixtures or wastes with a hydrocarbon fractionof gasoline or diesel fuel with a boiling point above 90° C. attemperatures between 90° C. and the boiling point of the hydrocarbonsolvent. The '312 patent application further describes contacting a hotpolyolefin solution with bleaching clay and/or activated carbon toremove foreign components from the solution. The '312 patent yet furtherdescribes cooling the solution to temperatures below 70° C. tocrystallize the polyolefin and then removing adhering solvent by heatingthe polyolefin above the melting point of the polyolefin, or evaporatingthe adhering solvent in a vacuum or passing a gas stream through thepolyolefin precipitate, and/or extraction of the solvent with an alcoholor ketone that boils below the melting point of the polyolefin.

In another example, U.S. Pat. No. 5,198,471 describes a method forseparating polymers from a physically commingled solid mixture (forexample waste plastics) containing a plurality of polymers using asolvent at a first lower temperature to form a first single phasesolution and a remaining solid component. The '471 patent furtherdescribes heating the solvent to higher temperatures to dissolveadditional polymers that were not solubilized at the first lowertemperature. The '471 patent describes filtration of insoluble polymercomponents.

In another example, U.S. Pat. No. 5,233,021 describes a method ofextracting pure polymeric components from a multi-component structure(for example waste carpeting) by dissolving each component at anappropriate temperature and pressure in a supercritical fluid and thenvarying the temperature and/or pressure to extract particular componentsin sequence. However, similar to the '471 patent, the '021 patent onlydescribes filtration of the precipitated component.

In another example, U.S. Pat. No. 5,739,270 describes a method andapparatus for continuously separating a polymer component of a plasticfrom contaminants and other components of the plastic using a co-solventand a working fluid. The co-solvent at least partially dissolves thepolymer and the second fluid (that is in a liquid, critical, orsupercritical state) solubilizes components from the polymer andprecipitates some of the dissolved polymer from the co-solvent. The '270patent further describes the step of filtering thethermoplastic-co-solvent (with or without the working fluid) to removeparticulate contaminants, such as glass particles.

The known solvent-based methods to purify contaminated polymers, asdescribed above, do not produce “virgin-like” polymer. In the previousmethods, co-dissolution and thus cross contamination of other polymersoften occurs. If adsorbent is used, a filtration and/or centrifugationstep is often employed to remove the used adsorbent from solution. Inaddition, isolation processes to remove solvent, such as heating, vacuumevaporation, and/or precipitation using a precipitating chemical areused to produce a polymer free of residual solvent.

Accordingly, a need still exists for an improved solvent-based method topurify contaminated polymers that uses a solvent that is readily andeconomically removed from the polymer, is relatively simple in terms ofthe number of unit operations, produces a polymer without a significantamount of polymeric cross contamination, produces a polymer that isessentially colorless, and produces a polymer that is essentiallyodorless.

SUMMARY OF THE INVENTION

A method for purifying a reclaimed polymer is disclosed. In oneembodiment, the method involves obtaining reclaimed polymer where thereclaimed polymer is selected from the group consisting of post-consumeruse polymers, post-industrial use polymers, and combinations thereof;contacting the reclaimed polymer at a temperature from about 80° C. toabout 280° C. and at a pressure from about 150 psig (1.03 MPa) to about8,000 psig (55.16 MPa) with a first fluid solvent having a standardboiling point less than about 70° C., to produce an extracted reclaimedpolymer; dissolving the extracted reclaimed polymer in a solventselected from the group consisting of the first fluid solvent, a secondfluid solvent, and mixtures thereof, at a temperature from about 90° C.to about 280° C. and a pressure from about 200 psig (1.38 MPa) to about9,000 psig (62.05 MPa) to produce a first solution comprising polymer,at least one dissolved contaminant, and at least one suspendedcontaminant; settling the first solution comprising polymer, at leastone dissolved contaminants, and at least one suspended contaminant at atemperature from about 90° C. to about 280° C. and at a pressure fromabout 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce asecond solution comprising polymer, at least one dissolved contaminant,and less of the at least one suspended contaminant; filtering the secondsolution at a temperature from about 90° C. to about 280° C. and at apressure from about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa)to produce a third solution comprising purer polymer, at least onedissolved contaminant, and even less of the at least one suspendedcontaminant; and separating the purer polymer from the third solution;and where the second fluid solvent has the same chemical composition ora different chemical composition as the first fluid solvent.

In another embodiment, the purer polymer is separated from the thirdsolution at a temperature from about 0° C. to about 280° C. and apressure from about 0 psig (0 MPa) to 2,000 psig (13.79 MPa). In anotherembodiment, the reclaimed polymer is dissolved in the fluid solvent, orfluid solvent mixture, at a mass percent concentration of at least 0.5%.In yet another embodiment, the reclaimed polymer is dissolved in thefluid solvent, or fluid solvent mixture, at a mass percent concentrationof at least 1%. In one embodiment, the reclaimed polymer is dissolved inthe fluid solvent, or fluid solvent mixture, at a mass percentconcentration of at least 2%. In another embodiment, the reclaimedpolymer is dissolved in the fluid solvent, or fluid solvent mixture, ata mass percent concentration of at least 3%. In yet another embodiment,the reclaimed polymer is dissolved in the fluid solvent, or fluidsolvent mixture, at a mass percent concentration of at least 4%. Instill another embodiment, the reclaimed polymer is dissolved in thefluid solvent, or fluid solvent mixture, at a mass percent concentrationof at least 5%. In one embodiment, the reclaimed polymer is dissolved inthe fluid solvent, or fluid solvent mixture, at a mass percentconcentration up to 20%. In another embodiment, the reclaimed polymer isdissolved in the fluid solvent, or fluid solvent mixture, at a masspercent concentration up to 18%. In yet another embodiment, thereclaimed polymer is dissolved in the fluid solvent, or fluid solventmixture, at a mass percent concentration up to 16%. In anotherembodiment, the reclaimed polymer is dissolved in the fluid solvent, orfluid solvent mixture, at a mass percent concentration up to 14%. In oneembodiment, the reclaimed polymer is dissolved in the fluid solvent, orfluid solvent mixture, at a mass percent concentration up to 12%.

In another embodiment, the reclaimed polymer is post-consumer recyclederived polymer. In another embodiment, the reclaimed polymer ispolystyrene. In another embodiment, the reclaimed polymer ispoly(dimethylsiloxane). In another embodiment, the reclaimed polymer isa polypropylene homopolymer or a primarily polypropylene copolymer. Inyet another embodiment, the reclaimed polymer is a polyethylenehomopolymer or a primarily polyethylene copolymer.

In one embodiment, the fluid solvent has a standard boiling point lessthan about 0° C. and greater than about −45° C. and a standard enthalpychange of vaporization of less than about +25 kJ/mol. In anotherembodiment, the fluid solvent is selected from the group consisting ofolefinic hydrocarbons, aliphatic hydrocarbons, and mixtures thereof. Inyet another embodiment, the aliphatic hydrocarbon is selected from thegroup consisting of C1-C6 aliphatic hydrocarbons and mixtures thereof.In still another embodiment, the aliphatic hydrocarbons and mixturesthereof is comprised of primarily C4 aliphatic hydrocarbons.

In another embodiment, the fluid solvent consists essentially of C4liquefied petroleum gas. In yet another embodiment, the fluid solventcomprises n-butane, butane isomers, or mixtures thereof. In stillanother embodiment, the fluid solvent comprises n-pentane, isomers ofpentane, or mixtures thereof.

In one embodiment, the temperature in the contacting, dissolving,settling and filtering steps is from about 110° C. to about 220° C. Inanother embodiment, the pressure in the contacting step is from about400 psig (2.76 MPa) to about 2,400 psig (16.55 MPa). In yet anotherembodiment, the pressure in the contacting step is less than about 1,100psig (7.58 MPa). In one embodiment, the pressure in the dissolving,settling, and filtering steps is from about 400 psig (2.76 MPa) to about6,000 (41.37 MPa).

In one embodiment, the filtering is conducted in an axial flowdirection. In another embodiment, the filtering is conducted in a radialflow direction. In yet another embodiment, the filtering is conducted ina candle-type filter apparatus. In another embodiment, the candle filterapparatus is pre-coated with a filtration aid. In one embodiment, thecandle filter apparatus is pre-coated with a filtration aid selectedfrom the group consisting of diatomaceous earth, perlite, cellulosicfiber, clay, activated carbon, alumina, silica, alumina silicate,zeolite, and mixtures thereof. In another embodiment, the candle filterapparatus is pre-coated with a filtration aid having a particle sizefrom about 10 μm to about 100 μm.

In another embodiment, the filtering comprises body feeding one or morefiltration aids. In yet another embodiment, the one or more filtrationaids is selected from the group consisting of diatomaceous earth,perlite, cellulosic fiber, clay, activated carbon, alumina, silica,alumina silicate, zeolite, and mixtures thereof.

In another embodiment, a method for purifying a reclaimed polymer isdisclosed. The method comprises obtaining the reclaimed polymer whereinthe reclaimed polymer is selected from the group consisting ofpost-consumer use polymers, post-industrial use polymers, andcombinations thereof; contacting the reclaimed polymer at a temperaturefrom about 80° C. to about 280° C. and at a pressure from about 150 psig(1.03 MPa) to about 8,000 psig (55.16 MPa) with a first fluid solventhaving a standard boiling point less than about 70° C., to produce anextracted reclaimed polymer; dissolving the extracted reclaimed polymerin a solvent selected from the group consisting of the first fluidsolvent, a second fluid solvent, and mixtures thereof, at a temperaturefrom about 90° C. to about 280° C. and a pressure from about 200 psig(1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a first solutioncomprising polymer, at least one dissolved contaminant, and at least onesuspended contaminant; settling the first solution comprising polymer,at least one dissolved contaminants, and at least one suspendedcontaminant at a temperature from about 90° C. to about 280° C. and at apressure from about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa)to produce a second solution comprising polymer, at least one dissolvedcontaminant, and less of the at least one suspended contaminant;filtering the second solution at a temperature from about 90° C. toabout 280° C. and at a pressure from about 200 psig (1.38 MPa) to about9,000 psig (62.05 MPa) to produce a third solution comprising purerpolymer, at least one dissolved contaminant, and even less of the atleast one suspended contaminant; and purifying by further filtering thethird solution at a temperature from about 90° C. to about 280° C. andat a pressure from about 200 psig (1.38 MPa) to about 9,000 psig (62.05MPa) by contacting the third solution with one or more solid media toproduce a fourth solution comprising purer polymer; and separating thepurer polymer from the fourth solution; and where the second fluidsolvent has the same chemical composition or a different chemicalcomposition as the first fluid solvent.

In another embodiment, the purer polymer is separated from the thirdsolution at a temperature from about 0° C. to about 280° C. and apressure from about 0 psig (0 MPa) to 2,000 psig (13.79 MPa). In yetanother embodiment, the reclaimed polymer is dissolved in the fluidsolvent, or fluid solvent mixture, at a mass percent concentration of atleast 0.5%. In one embodiment, the reclaimed polymer is dissolved in thefluid solvent, or fluid solvent mixture, at a mass percent concentrationof at least 1%. In another embodiment, the reclaimed polymer isdissolved in the fluid solvent, or fluid solvent mixture, at a masspercent concentration of at least 2%. In yet another embodiment, thereclaimed polymer is dissolved in the fluid solvent, or fluid solventmixture, at a mass percent concentration of at least 3%. In stillanother embodiment, the reclaimed polymer is dissolved in the fluidsolvent, or fluid solvent mixture, at a mass percent concentration of atleast 4%. In one embodiment, the reclaimed polymer is dissolved in thefluid solvent, or fluid solvent mixture, at a mass percent concentrationof at least 5%. In another embodiment, the reclaimed polymer isdissolved in the fluid solvent, or fluid solvent mixture, at a masspercent concentration up to 20%. In yet another embodiment, thereclaimed polymer is dissolved in the fluid solvent, or fluid solventmixture, at a mass percent concentration up to 18%. In still anotherembodiment, the reclaimed polymer is dissolved in the fluid solvent, orfluid solvent mixture, at a mass percent concentration up to 16%. In oneembodiment, the reclaimed polymer is dissolved in the fluid solvent, orfluid solvent mixture, at a mass percent concentration up to 14%. Inanother embodiment, the reclaimed polymer is dissolved in the fluidsolvent, or fluid solvent mixture, at a mass percent concentration up to12%.

In another embodiment, the reclaimed polymer is post-consumer recyclederived polymer. In another embodiment, the reclaimed polymer ispolystyrene. In another embodiment, the reclaimed polymer ispoly(dimethylsiloxane). In another embodiment, the reclaimed polymer isa polypropylene homopolymer or a primarily polypropylene copolymer. Inyet another embodiment, the reclaimed polymer is a polyethylenehomopolymer or a primarily polyethylene copolymer.

In another embodiment, the fluid solvent has a standard boiling pointless than about 0° C. and greater than about −45° C. and a standardenthalpy change of vaporization of less than about +25 kJ/mol. In yetanother embodiment, the fluid solvent is selected from the groupconsisting of olefinic hydrocarbons, aliphatic hydrocarbons, andmixtures thereof. In still another embodiment, the aliphatic hydrocarbonis selected from the group consisting of C1-C6 aliphatic hydrocarbonsand mixtures thereof. In one embodiment, the aliphatic hydrocarbons andmixtures thereof is comprised of primarily C4 aliphatic hydrocarbons. Inanother embodiment, the fluid solvent consists essentially of C4liquefied petroleum gas. In yet another embodiment, the fluid solventcomprises n-butane, butane isomers, or mixtures thereof. In stillanother embodiment, the fluid solvent comprises n-pentane, pentaneisomers, or mixtures thereof.

In one embodiment, the temperature in the contacting, dissolving,settling and filtering steps is from about 110° C. to about 220° C. Inanother embodiment, the pressure in the contacting step is from about400 psig (2.76 MPa) to about 2,400 psig (16.55 MPa). In yet anotherembodiment, the pressure in the contacting step is less than about 1,100psig (7.58 MPa).

In another embodiment, the pressure in the dissolving, settling, andfiltering steps is from about 400 psig (2.76 MPa) to about 6,000 (41.37MPa). In yet another embodiment, the filtering is conducted in an axialflow direction. In still another embodiment, the filtering is conductedin a radial flow direction. In one embodiment, the filtering isconducted in a candle-type filter apparatus. In another embodiment, thecandle filter apparatus is pre-coated with a filtration aid. In yetanother embodiment, the candle filter apparatus is pre-coated with afiltration aid selected from the group consisting of diatomaceous earth,perlite, cellulosic fiber, clay, activated carbon, alumina, silica,alumina silicate, zeolite, and mixtures thereof. In still anotherembodiment, the candle filter apparatus is pre-coated with a filtrationaid having a particle size from about 10 μm to about 100 μm. In oneembodiment, the filtering comprises body feeding one or more filtrationaids. In another embodiment, the one or more filtration aids is selectedfrom the group consisting of diatomaceous earth, perlite, cellulosicfiber, clay, activated carbon, alumina, silica, alumina silicate,zeolite, and mixtures thereof.

In one embodiment, the solid media is selected from the group consistingof inorganic substances. In another embodiment, the one or more solidmedia is selected from the group consisting of oxides of silicon, oxidesof aluminum, oxides of iron, aluminum silicates, amorphous volcanicglasses, and mixtures thereof. In yet another embodiment, the one ormore solid media is selected from the group consisting of silica gel,diatomite, sand, quartz, activated alumina, perlite, fuller's earth,bentonite, and mixtures thereof. In still another embodiment, thecontacting of the third solution with one or more solid media isperformed in a packed bed of one or more solid media.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block flow diagram showing the major steps of one embodimentof the present invention.

FIG. 2 is a calibration curve for the calculation of polyethylenecontent in polypropylene using enthalpy values from DSC measurements.

FIG. 3A is a schematic of the experimental apparatus used in theextraction step.

FIG. 3B is a schematic of the experimental apparatus used fordissolution, sedimentation, filtration, and purification.

DETAILED DESCRIPTION OF THE INVENTION I. Definitions

As used herein, the term “reclaimed polymer” refers to a polymer usedfor a previous purpose and then recovered for further processing.

As used herein, the term “post-consumer” refers to a source of materialthat originates after the end consumer has used the material in aconsumer good or product.

As used herein, the term “post-consumer recycle” (PCR) refers to amaterial that is produced after the end consumer has used the materialand has disposed of the material in a waste stream.

As used herein, the term “post-industrial” refers to a source of amaterial that originates during the manufacture of a good or product.

As used herein, the term “fluid solvent” refers to a substance that mayexist in the liquid state under specified conditions of temperature andpressure. In some embodiments the fluid solvent may be a predominantlyhomogenous chemical composition of one molecule or isomer, while inother embodiments, the fluid solvent may be a mixture of severaldifferent molecular compositions or isomers. Further, in someembodiments of the present invention, the term “fluid solvent” may alsoapply to substances that are at, near, or above the critical temperatureand critical pressure (critical point) of that substance. It is wellknown to those having ordinary skill in the art that substances abovethe critical point of that substance are known as “supercritical fluids”which do not have the typical physical properties (i.e. density) of aliquid.

As used herein, the term “dissolved” means at least partialincorporation of a solute (polymeric or non-polymeric) in a solvent atthe molecular level. Further, the thermodynamic stability of thesolute/solvent solution can be described by the following equation 1:ΔG _(mix) =ΔH _(m) −TΔS _(mix)  Equation 1where ΔG_(mix) is the Gibbs free energy change of mixing of a solutewith a solvent, ΔH_(mix) is the enthalpy change of mixing, T is theabsolute temperature, and ΔS_(mix) is the entropy of mixing. To maintaina stable solution of a solute in a solvent, the Gibbs free energy mustbe negative and at a minimum. Thus, any combination of solute andsolvent that minimize a negative Gibbs free energy at appropriatetemperatures and pressures can be used for the present invention.

As used herein, the term “standard boiling point” refers to the boilingtemperature at an absolute pressure of exactly 100 kPa (1 bar, 14.5psia, 0.9869 atm) as established by the International Union of Pure andApplied Chemistry (IUPAC).

As used herein, the term “standard enthalpy change of vaporization”refers to the enthalpy change required to transform a specified quantityof a substance from a liquid into a vapor at the standard boiling pointof the substance.

As used herein, the term “polymer solution” refers to a solution ofpolymer dissolved in a solvent. The polymer solution may containundissolved matter (e.g. at least one suspended contaminant) and thusthe polymer solution may also be a “slurry” of undissolved mattersuspended in a solution of polymer dissolved in a solvent.

As used herein, the terms “sedimentation” and “settling” refer to thetendency of particles within a suspension to separate from a liquid inresponse to a force (typically a gravitational force) acting upon theparticles.

As used herein, the term “suspended contaminant” refers to an unwantedor undesired constituent present throughout the bulk of medium of aheterogeneous mixture.

As used herein, the term “dissolved contaminant” refers to an unwantedor undesired constituent at least partially incorporated into a solventat the molecular level.

As used herein, the term “filtration” and “filtering” refers to aseparation of at least one dissolved and/or suspended contaminant from afluid by using mechanical and/or physical operations (e.g. passing thecontaminated fluid through a filtration system). As used herein, theterms “filtration system” and “filter” are used interchangeably.

As used herein, when referring to a solution, the term “less suspendedcontaminant” refers to a subsequent condition of the solution, withrespect to a prior condition (e.g. prior to a contaminant removal step),in which the prior solution had a relatively greater quantity of thesuspended contaminant.

As used herein, when referring to a solution, the term “comprising evenless of a suspended contaminant” refers to a subsequent condition of thesolution, with respect to a prior condition (e.g. “comprising less of asuspended contaminant”), in which the prior solution had a relativelygreater quantity of the suspended contaminant.

As used herein, the terms “solid media” and “solid medium” refer to asubstance that exists in the solid state under the conditions of use.The solid media may be crystalline, semi-crystalline, or amorphous. Thesolid media may be granular and may be supplied in different shapes(i.e. spheres, cylinders, pellets, etc.). If the solid media aregranular, the particle size and particle size distribution of solidmedia may be defined by the mesh size used to classify the granularmedia. An example of standard mesh size designations can be found in theAmerican Society for Testing and Material (ASTM) standard ASTM Ell“Standard Specification for Woven Wire Test Sieve Cloth and TestSieves.” The solid media may also be a non-woven fibrous mat or a woventextile.

As used herein, the term “purer polymer solution” refers to a polymersolution having less of one or more contaminants relative to the samepolymer solution prior to a purification step.

As used herein, the term “extraction” refers to the practice oftransferring a solute species from a liquid phase (or solid matrix)across a phase boundary to a separate immiscible liquid phase. Thedriving force(s) for extraction are described by partition theory.

As used herein, the term “extracted” refers to a material having less ofone or more solute species relative to the same material prior to anextraction step. As used herein, the term “extracted reclaimed polymer”refers to a reclaimed polymer having less of one or more solute speciesrelative to the same reclaimed polymer prior to an extraction step.

As used herein, the term “virgin-like” means essentiallycontaminant-free, pigment-free, odor-free, homogenous, and similar inproperties to virgin polymers.

As used herein, the term “primarily polypropylene copolymer” refers acopolymer with greater than 70 mol % of propylene repeating units.

As used herein, the term “primarily polyethylene copolymer” refers acopolymer with greater than 70 mol % of ethylene repeating units.

As used herein, any reference to international units of pressure (e.g.MPa) refers to gauge pressure.

As used herein, the term “axial flow direction” refers to a fluidflowing parallel to the long axis of a filter medium.

As used herein, the term “radial flow direction” refers to a fluidflowing perpendicular to the long axis of a filter medium.

As used herein, the terms “candle-type filter apparatus” and “candlefilter,” more generally referred to as an “external-cake tubularfilter,” refer to an apparatus that uses pressure to separate solidsfrom a liquid. A detailed description of candle-type filters, as well asother solid-liquid separation apparatuses, is provided in the followingreference: Perry, Robert H, and Don W. Green. Perry's ChemicalEngineers' Handbook. New York: McGraw-Hill, 2008. Print.

As used herein, the term “pre-coated with filtration aid” refers to asolid-liquid separation apparatus where the filtration medium iscomprised of a rigid or semi-rigid screen on which a layer or layers offine solid material (e.g. diatomaceous earth, perlite, cellulosic fiber,clay, activated carbon, alumina, silica, alumina silicate, zeolite, andmixtures thereof) are deposited.

As used herein, the term “body feeding” or “body fed” refers to theaddition of filtration aid to a fluid before the fluid is filtered.

II. Method for Purifying Contaminated Polymers

Surprisingly, it has been found that contaminated high molecular weightpolymer solutions are purified by filtration. This process, exemplifiedin FIG. 1, comprises 1) obtaining a reclaimed polymer (step a in FIG.1), followed by 2) extracting the polymer with a fluid solvent at anextraction temperature (T_(E)) and at an extraction pressure (P_(E))(step b in FIG. 1), followed by 3) dissolving the polymer in a fluidsolvent at a dissolution temperature (T_(D)) and at a dissolutionpressure (P_(D)) (step c in FIG. 1), followed by 4) settling the polymersolution at a dissolution temperature (T_(D)) and at a dissolutionpressure (P_(D)) (step d in FIG. 1), followed by 5) filtering thepolymer solution dissolution temperature (T_(D)) and at a dissolutionpressure (P_(D)) (step e in FIG. 1), followed by 6) purifying thepolymer solution with solid media at a dissolution temperature (T_(D))and at a dissolution pressure (P_(D)) (step fin FIG. 1), followed byseparation of the polymer from the fluid solvent (step g in FIG. 1).Note that the aforementioned terms T_(E), P_(E), T_(D), P_(D) may varyin value from one step to another.

In one embodiment of the present invention, the purified polymer, whichmay be sourced from post-consumer waste streams, are essentiallycontaminant-free, pigment-free, odor-free, homogenous, and similar inproperties to virgin polymer.

Reclaimed Polymer

In one embodiment of the present invention, a method for purifyingreclaimed polymers includes obtaining a reclaimed polymer. For thepurposes of the present invention, the reclaimed polymer is sourced frompost-consumer, post-industrial, post-commercial, and/or other specialwaste streams. For example, post-consumer waste polymers can be derivedfrom curbside recycle streams where end-consumers place used polymersfrom packages and products into a designated bin for collection by awaste hauler or recycler. Post-consumer waste polymers can also bederived from in-store “take-back” programs where the consumer bringswaste polymers into a store and places the waste polymers in adesignated collection bin. An example of post-industrial waste polymerscan be waste polymers produced during the manufacture or shipment of agood or product that are collected as unusable material by themanufacturer (i.e. trim scraps, out of specification material, start upscrap). An example of waste polymers from a special waste stream can bewaste polymers derived from the recycling of electronic waste, alsoknown as “e-waste.” Another example of waste polymers from a specialwaste stream can be waste polymers derived from the recycling ofautomobiles. Another example of waste polymers from a special wastestream can be waste polymers derived from the recycling of usedcarpeting and textiles.

For the purposes of the present invention, the reclaimed polymer is ahomogenous composition of an individual polymer or a mixture of severaldifferent polymer compositions. Non-limiting examples of reclaimedpolymeric compositions are homopolymers and copolymers of polyolefins,such as polyethylene and isotactic polypropylene, polyesters, such aspoly(ethylene terephthalate), vinyl polymers, such as poly(vinylchloride), styrenic polymers, such as polystyrene, polyamides, such aspoly(hexamethylene adapamide), polycarbonates, such as poly(bisphenol-Acarbonate), polyacrylates, such as poly(methyl methacrylate),polysiloxanes, such as poly(dimethylsiloxane), thermoplastic elastomers,such as styrene-butadiene block copolymers and ethylene-propylenerubber, and other dissolvable polymers that may be apparent to thosehaving ordinary skill in the art.

The reclaimed polymer may also contain various pigments, dyes, processaides, stabilizing additives, fillers, and other performance additivesthat were added to the polymer during polymerization or conversion ofthe original polymer to the final form of an article. Non-limitingexamples of pigments are organic pigments, such as copperphthalocyanine, inorganic pigments, such as titanium dioxide, and otherpigments that may be apparent to those having ordinary skill in the art.A non-limiting example of an organic dye is Basic Yellow 51.Non-limiting examples of process aides are antistatic agents, such asglycerol monostearate and slip-promoting agents, such as erucamide. Anon-limiting example of a stabilizing additive isoctadecyl-3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate. Non-limitingexamples of fillers are calcium carbonate, talc, and glass fibers.

Solvent

The fluid solvent of the present invention has a standard boiling pointless than about 70° C. Pressurization maintains solvents, which havestandard boiling points below the operating temperature range of thepresent invention, in a state in which there is little or no solventvapor. In one embodiment, the fluid solvent with a standard boilingpoint less than about 70° C. is selected from the group consisting ofcarbon dioxide, ketones, alcohols, ethers, esters, alkenes, alkanes, andmixtures thereof. Non-limiting examples of fluid solvents with standardboing points less than about 70° C. are carbon dioxide, acetone,methanol, dimethyl ether, diethyl ether, ethyl methyl ether,tetrahydrofuran, methyl acetate, ethylene, propylene, 1-butene,2-butene, isobutylene, 1-pentene, 2-pentene, branched isomers ofpentene, 1-hexene, 2-hexene, methane, ethane, propane, n-butane,isobutane, n-pentane, isopentane, neopentane, n-hexane, isomers ofisohexane, and other substances that may be apparent to those havingordinary skill in the art.

The selection of the appropriate solvent or solvent mixture will dependon which reclaimed polymer or polymer mixture is being purified by thepresent invention. Further, the selection of the polymer being purifiedand the corresponding fluid solvent used will dictate the temperatureand pressure ranges used to perform the steps of the present invention.A review of polymer phase behavior in solvents of the kind described bythe present invention is provided in the following reference: McHugh etal. (1999) Chem. Rev. 99:565-602.

Extraction

In one embodiment of the present invention, a method for purifyingreclaimed polymers includes contacting a reclaimed polymer with a fluidsolvent at a temperature and at a pressure wherein the polymer isessentially insoluble in the fluid solvent. Although not wishing to bebound by any theory, applicants believe that the temperature andpressure-dependent solubility can be controlled in such a way to preventthe fluid solvent from fully solubilizing the polymer, however, thefluid solvent can diffuse into the polymer and extract any extractablecontamination. The extractable contamination may be residual processingaides added to the polymer, residual product formulations whichcontacted the polymer, such as perfumes and flavors, dyes, and any otherextractable material that may have been intentionally added orunintentionally became incorporated into the polymer, for example,during waste collection and subsequent accumulation with other wastematerials.

In one embodiment, the controlled extraction may be accomplished byfixing the temperature of the polymer/fluid solvent system and thencontrolling the pressure below a pressure, or pressure range, where thepolymer dissolves in the fluid solvent. In another embodiment, thecontrolled extraction is accomplished by fixing the pressure of thepolymer/solvent system and then controlling the temperature below atemperature, or temperature range where the polymer dissolves in thefluid solvent. The temperature and pressure-controlled extraction of thepolymer with a fluid solvent uses a suitable pressure vessel and may beconfigured in a way that allows for continuous extraction of the polymerwith the fluid solvent. In one embodiment of the present invention, thepressure vessel may be a continuous liquid-liquid extraction columnwhere molten polymer is pumped into one end of the extraction column andthe fluid solvent is pumped into the same or the opposite end of theextraction column. In another embodiment, the fluid containing extractedcontamination is removed from the process. In another embodiment, thefluid containing extracted contamination is purified, recovered, andrecycled for use in the extraction step or a different step in theprocess. In one embodiment of the present invention, the extraction maybe performed as a batch method, wherein the reclaimed polymer is fixedin a pressure vessel and the fluid solvent is continuously pumpedthrough the fixed polymer phase. The extraction time or the amount offluid solvent used will depend on the desired purity of the final purerpolymer and the amount of extractable contamination in the startingreclaimed polymer. In another embodiment, the fluid containing extractedcontamination is contacted with solid media in a separate step asdescribed in the “Purification” section below. In another embodiment, amethod for purifying reclaimed polymers includes contacting a reclaimedpolymer with a fluid solvent at a temperature and at a pressure whereinthe polymer is molten and in the liquid state. In another embodiment,the reclaimed polymer is contacted with the fluid solvent at atemperature and at a pressure wherein the polymer is in the solid state.

In one embodiment, a method for purifying reclaimed polymers includescontacting polymers with a fluid solvent at a temperature and a pressurewherein the polyethylene remains essentially undissolved. In oneembodiment, a method for purifying reclaimed polymers includescontacting a polymer with a fluid solvent at a temperature and apressure wherein the polymer remains essentially undissolved. In anotherembodiment, a method for purifying reclaimed polymers includescontacting a polymer with a fluid solvent at a temperature from about80° C. to about 280° C. In yet another embodiment, a method forpurifying reclaimed polymers includes contacting a polymer with a fluidsolvent at a temperature from about 110° C. to about 220° C. In oneembodiment, a method for purifying reclaimed polymers includescontacting a polymer with a fluid solvent at a pressure from about 150psig (1.03 MPa) to about 8,000 psig (55.16 MPa). In another embodiment,a method for purifying reclaimed polymers includes contacting a polymerwith a fluid solvent at a pressure from about 400 psig (2.76 MPa) toabout 2,400 psig (16.55 MPa).

In another embodiment, a method for purifying reclaimed polymersincludes contacting polyethylene with n-butane at a temperature fromabout 80° C. to about 280° C. In another embodiment, a method forpurifying reclaimed polymers includes contacting polyethylene withn-butane at a temperature from about 100° C. to about 220° C. In anotherembodiment, a method for purifying reclaimed polymers includescontacting polyethylene with n-butane at a temperature from about 130°C. to about 180° C. In another embodiment, a method for purifyingreclaimed polymers includes contacting polyethylene with n-butane at apressure from about 400 psig (2.76 MPa) to about 6,000 psig (41.37 MPa).In another embodiment, a method for purifying reclaimed polymersincludes contacting polyethylene with n-butane at a pressure from about800 psig (5.52 MPa) to about 5,000 psig (34.47 MPa). In anotherembodiment, a method for purifying reclaimed polymers includescontacting polyethylene with n-butane at a pressure from about 1,000psig (6.89 MPa) to about 4,500 psig (31.03 MPa).

In another embodiment, a method for purifying reclaimed polymersincludes contacting polyethylene with n-pentane at a temperature fromabout 80° C. to about 280° C. In another embodiment, a method forpurifying reclaimed polymers includes contacting polyethylene withn-pentane at a temperature from about 100° C. to about 220° C. Inanother embodiment, a method for purifying reclaimed polymers includescontacting polyethylene with n-pentane at a temperature from about 130°C. to about 180° C. In another embodiment, a method for purifyingreclaimed polymers includes contacting polyethylene with n-pentane at apressure from about 400 psig (2.78 MPa) to about 3,000 psig (20.68 MPa).In another embodiment, a method for purifying reclaimed polymersincludes contacting polyethylene with n-pentane at a pressure from about800 psig (5.52 MPa) to about 2,800 psig (19.31 MPa). In anotherembodiment, a method for purifying reclaimed polymers includescontacting polyethylene with n-pentane at a pressure from about 1,000psig (6.89 MPa) to about 2,400 psig (16.55 MPa).

In another embodiment, a method for purifying reclaimed polymersincludes contacting polypropylene with n-butane at a temperature fromabout 80° C. to about 280° C. In another embodiment, a method forpurifying reclaimed polymers includes contacting polypropylene withn-butane at a temperature from about 100° C. to about 220° C. In anotherembodiment, a method for purifying reclaimed polymers includescontacting polypropylene with n-butane at a temperature from about 130°C. to about 180° C. In another embodiment, a method for purifyingreclaimed polymers includes contacting polypropylene with n-butane at apressure from about 150 psig (1.03 MPa) to about 3,000 psig (20.68 MPa).In another embodiment, a method for purifying reclaimed polymersincludes contacting polypropylene with n-butane at a pressure from about1,000 psig (6.89 MPa) to about 2,750 psig (18.96 MPa). In anotherembodiment, a method for purifying reclaimed polymers includescontacting polypropylene with n-butane at a pressure from about 1,500psig (10.34 MPa) to about 2,500 psig (17.24 MPa).

In another embodiment, a method for purifying reclaimed polymersincludes contacting polypropylene with propane at a temperature fromabout 80° C. to about 280° C. In another embodiment, a method forpurifying reclaimed polymers includes contacting polypropylene withpropane at a temperature from about 100° C. to about 220° C. In anotherembodiment, a method for purifying reclaimed polymers includescontacting polypropylene with propane at a temperature from about 130°C. to about 180° C. In another embodiment, a method for purifyingreclaimed polymers includes contacting polypropylene with propane at apressure from about 200 psig (1.38 MPa) to about 8,000 psig (55.16 MPa).In another embodiment, a method for purifying reclaimed polymersincludes contacting polypropylene with propane at a pressure from about1,000 psig (6.89 MPa) to about 6,000 psig (41.37 MPa). In anotherembodiment, a method for purifying reclaimed polymers includescontacting polypropylene with propane at a pressure from about 2,000psig (13.79 MPa) to about 4,000 psig (27.58 MPa).

In one embodiment, a method for purifying reclaimed polymers includescontacting polystyrene with a fluid solvent at a temperature and apressure wherein the polystyrene remains essentially undissolved. Inanother embodiment, a method for purifying reclaimed polymers includescontacting polystyrene with n-butane at a temperature from about 90° C.to about 280° C. In another embodiment, a method for purifying reclaimedpolymers includes contacting polystyrene with n-butane at a temperaturefrom about 100° C. to about 220° C. In another embodiment, a method forpurifying reclaimed polymers includes contacting polystyrene withn-butane at a temperature from about 120° C. to about 180° C. In anotherembodiment, a method for purifying reclaimed polymers includescontacting polystyrene with n-butane at a pressure from about 500 psig(3.45 MPa) to about 5,000 psig (34.47 MPa). In another embodiment, amethod for purifying reclaimed polymers includes contacting polystyrenewith n-butane at a pressure from about 1,000 psig (6.89 MPa) to about4,000 psig (27.58 MPa). In another embodiment, a method for purifyingreclaimed polymers includes contacting polystyrene with n-butane at apressure from about 2,000 psig (13.79 MPa) to about 3,000 psig (20.68MPa).

In one embodiment, a method for purifying reclaimed polymers includescontacting poly(dimethylsiloxane) with a fluid solvent at a temperatureand a pressure wherein the poly(dimethylsiloxane) remains essentiallyundissolved. In another embodiment, a method for purifying reclaimedpolymers includes contacting poly(dimethylsiloxane) with n-butane at atemperature from about 100° C. to about 280° C. In another embodiment, amethod for purifying reclaimed polymers includes contactingpoly(dimethylsiloxane) with n-butane at a temperature from about 115° C.to about 220° C. In another embodiment, a method for purifying reclaimedpolymers includes contacting poly(dimethylsiloxane) with n-butane at atemperature from about 120° C. to about 180° C. In another embodiment, amethod for purifying reclaimed polymers includes contactingpoly(dimethylsiloxane) with n-butane at a pressure from about 200 psig(1.38 MPa) to about 1,800 psig (12.41 MPa). In another embodiment, amethod for purifying reclaimed polymers includes contactingpoly(dimethylsiloxane) with n-butane at a pressure from about 300 psig(2.07 MPa) to about 1,500 psig (10.34 MPa). In another embodiment, amethod for purifying reclaimed polymers includes contactingpoly(dimethylsiloxane) with n-butane at a pressure from about 500 psig(3.45 MPa) to about 1,000 psig (6.89 MPa).

Dissolution

In one embodiment of the present invention, a method for purifyingreclaimed polymers includes dissolving the reclaimed polymer in a fluidsolvent at a temperature and at a pressure wherein the polymer isdissolved in the fluid solvent. Although not wishing to be bound by anytheory, applicants believe that the temperature and pressure can becontrolled in such a way to enable thermodynamically favorabledissolution of the reclaimed polymer in a fluid solvent. Furthermore,the temperature and pressure can be controlled in such a way to enabledissolution of a particular polymer or polymer mixture while notdissolving other polymers or polymer mixtures. This controllabledissolution enables the separation of polymers from polymer mixtures.

In one embodiment of the present invention, a method for purifyingreclaimed polymers includes dissolving contaminated reclaimed polymersin a solvent that does not dissolve the contaminants under the sameconditions of temperature and pressure. The contaminants may includepigments, fillers, dirt, and other polymers. These contaminants arereleased from the reclaimed polymer upon dissolution and then removedfrom the polymer solution via a subsequent solid-liquid separation step.In one embodiment of the present invention, a method for purifyingreclaimed polymers includes dissolving polyethylene in a fluid solventat a temperature and at a pressure wherein the polyethylene is dissolvedin the fluid solvent. In another embodiment, a method for purifyingreclaimed polymers includes dissolving a polymer in a fluid solvent at atemperature from about 90° C. to about 280° C. In yet anotherembodiment, a method for purifying reclaimed polymers includesdissolving a polymer in a fluid solvent at a temperature from about 110°C. to about 220° C. In one embodiment, a method for purifying reclaimedpolymers includes dissolving a polymer in a fluid solvent at a pressurefrom about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa). Inanother embodiment, a method for purifying reclaimed polymers includesdissolving a polymer in a fluid solvent at a pressure from about 400psig (2.76 MPa) to about 2,600 psig (17.93 MPa).

In another embodiment, a method for purifying reclaimed polymersincludes dissolving polyethylene in n-butane at a temperature from about90° C. to about 280° C. In another embodiment, a method for purifyingreclaimed polymers includes dissolving polyethylene in n-butane at atemperature from about 100° C. to about 220° C. In another embodiment, amethod for purifying reclaimed polymers includes dissolving polyethylenein n-butane at a temperature from about 130° C. to about 180° C. Inanother embodiment, a method for purifying reclaimed polymers includesdissolving polyethylene in n-butane at a pressure from about 4,000 psig(27.58 MPa) to about 8,000 psig (55.16 MPa). In another embodiment, amethod for purifying reclaimed polymers includes dissolving polyethylenein n-butane at a pressure from about 4,200 psig (28.96 MPa) to about7,000 psig (48.26 MPa). In another embodiment, a method for purifyingreclaimed polymers includes dissolving polyethylene in n-butane at apressure from about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37MPa). In another embodiment, a method for purifying reclaimed polymersincludes dissolving polyethylene in n-butane at a mass percentconcentration of at least 0.5%. In another embodiment, the polyethyleneis dissolved at a mass percent concentration of at least 1%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration of at least 2%. In another embodiment, the polyethylene isdissolved at a mass percent concentration of at least 3%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration of at least 4%. In another embodiment, the polyethylene isdissolved at a mass percent concentration of at least 5%. In anotherembodiment, a method for purifying reclaimed polymers includesdissolving polyethylene in n-butane at a mass percent concentration upto 20%. In another embodiment, the polyethylene is dissolved at a masspercent concentration up to 18%. In another embodiment, the polyethyleneis dissolved at a mass percent concentration up to 16%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration up to 14%. In another embodiment, the polyethylene isdissolved at a mass percent concentration up to 12%.

In another embodiment, a method for purifying reclaimed polymersincludes dissolving polyethylene in propane at a temperature from about90° C. to about 280° C. In another embodiment, a method for purifyingreclaimed polymers includes dissolving polyethylene in propane at atemperature from about 100° C. to about 220° C. In another embodiment, amethod for purifying reclaimed polymers includes dissolving polyethylenein propane at a temperature from about 130° C. to about 180° C. Inanother embodiment, a method for purifying reclaimed polymers includesdissolving polyethylene in n-pentane at a pressure from about 800 psig(5.52 MPa) to about 4,000 psig (27.58 MPa). In another embodiment, amethod for purifying reclaimed polymers includes dissolving polyethylenein n-pentane at a pressure from about 900 psig (6.21 MPa) to about 3,000psig (20.68 MPa). In another embodiment, a method for purifyingreclaimed polymers includes dissolving polyethylene in n-pentane at apressure from about 1,000 psig (6.89 MPa) to about 2,400 psig (16.55MPa). In another embodiment, a method for purifying reclaimed polymersincludes dissolving polyethylene in n-pentane at a mass percentconcentration of at least 0.5%. In another embodiment, the polyethyleneis dissolved at a mass percent concentration of at least 1%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration of at least 2%. In another embodiment, the polyethylene isdissolved at a mass percent concentration of at least 3%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration of at least 4%. In another embodiment, the polyethylene isdissolved at a mass percent concentration of at least 5%. In anotherembodiment, a method for purifying reclaimed polymers includesdissolving polyethylene in n-pentane at a mass percent concentration upto 20%. In another embodiment, the polyethylene is dissolved at a masspercent concentration up to 18%. In another embodiment, the polyethyleneis dissolved at a mass percent concentration up to 16%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration up to 14%. In another embodiment, the polyethylene isdissolved at a mass percent concentration up to 12%.

In one embodiment, a method for purifying reclaimed polymers includesdissolving polypropylene in a fluid solvent at a temperature and apressure wherein the polypropylene is dissolved in the fluid solvent. Inanother embodiment, a method for purifying reclaimed polymers includesdissolving polypropylene in n-butane at a temperature from about 90° C.to about 280° C. In another embodiment, a method for purifying reclaimedpolymers includes dissolving polypropylene in n-butane at a temperaturefrom about 100° C. to about 220° C. In another embodiment, a method forpurifying reclaimed polymers includes dissolving polypropylene inn-butane at a temperature from about 130° C. to about 180° C. In anotherembodiment, a method for purifying reclaimed polymers includesdissolving polypropylene in n-butane at a pressure from about 350 psig(2.41 MPa) to about 4,000 psig (27.57 MPa). In another embodiment, amethod for purifying reclaimed polymers includes dissolvingpolypropylene in n-butane at a pressure from about 1,000 psig (6.89 MPa)to about 3,500 psig (24.13 MPa). In another embodiment, a method forpurifying reclaimed polymers includes dissolving polypropylene inn-butane at a pressure from about 2,000 psig (13.79 MPa) to about 3,000psig (20.68 MPa). In another embodiment, a method for purifyingreclaimed polymers includes dissolving polypropylene in n-butane at amass percent concentration of at least 0.5%. In another embodiment, thepolypropylene is dissolved at a mass percent concentration of at least1%. In another embodiment, the polypropylene is dissolved at a masspercent concentration of at least 2%. In another embodiment, thepolypropylene is dissolved at a mass percent concentration of at least3%. In another embodiment, the polypropylene is dissolved at a masspercent concentration of at least 4%. In another embodiment, thepolypropylene is dissolved at a mass percent concentration of at least5%. In another embodiment, a method for purifying reclaimed polymersincludes dissolving polypropylene in n-butane at a mass percentconcentration up to 20%. In another embodiment, the polypropylene isdissolved at a mass percent concentration up to 18%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration up to 16%. In another embodiment, the polypropylene isdissolved at a mass percent concentration up to 14%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration up to 12%.

In another embodiment, a method for purifying reclaimed polymersincludes dissolving polypropylene in propane at a temperature from about90° C. to about 280° C. In another embodiment, a method for purifyingreclaimed polymers includes dissolving polypropylene in propane at atemperature from about 100° C. to about 220° C. In another embodiment, amethod for purifying reclaimed polymers includes dissolvingpolypropylene in propane at a temperature from about 130° C. to about180° C. In another embodiment, a method for purifying reclaimed polymersincludes dissolving polypropylene in propane at a pressure from about2,000 psig (13.79 MPa) to about 8,000 psig (55.16 MPa). In anotherembodiment, a method for purifying reclaimed polymers includesdissolving polypropylene in propane at a pressure from about 3,000 psig(20.68 MPa) to about 6,000 psig (41.37 MPa). In another embodiment, amethod for purifying reclaimed polymers includes dissolvingpolypropylene in propane at a pressure from about 3,500 psig (24.13 MPa)to about 5,000 psig (34.47 MPa). In another embodiment, a method forpurifying reclaimed polymers includes dissolving polypropylene inpropane at a mass percent concentration of at least 0.5%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration of at least 1%. In another embodiment, the polypropyleneis dissolved at a mass percent concentration of at least 2%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration of at least 3%. In another embodiment, the polypropyleneis dissolved at a mass percent concentration of at least 4%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration of at least 5%. In another embodiment, a method forpurifying reclaimed polymers includes dissolving polypropylene inpropane at a mass percent concentration up to 20%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration up to 18%. In another embodiment, the polypropylene isdissolved at a mass percent concentration up to 16%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration up to 14%. In another embodiment, the polypropylene isdissolved at a mass percent concentration up to 12%.

In one embodiment, a method for purifying reclaimed polymers includesdissolving polystyrene in a fluid solvent at a temperature and apressure wherein the polystyrene is dissolved in the fluid solvent. Inanother embodiment, a method for purifying reclaimed polymers includesdissolving polystyrene in n-butane at a temperature from about 90° C. toabout 280° C. In another embodiment, a method for purifying reclaimedpolymers includes dissolving polystyrene in n-butane at a temperaturefrom about 100° C. to about 220° C. In another embodiment, a method forpurifying reclaimed polymers includes dissolving polystyrene in n-butaneat a temperature from about 130° C. to about 180° C. In anotherembodiment, a method for purifying reclaimed polymers includesdissolving polystyrene in n-butane at a pressure from about 1,000 psig(6.89 MPa) to about 9,000 psig (62.05 MPa). In another embodiment, amethod for purifying reclaimed polymers includes dissolving polystyrenein n-butane at a pressure from about 2,000 psig (13.79 MPa) to about8,000 psig (55.16 MPa). In another embodiment, a method for purifyingreclaimed polymers includes dissolving polystyrene in n-butane at apressure from about 4,500 psig (31.03 MPa) to about 7,500 psig (51.71MPa). In another embodiment, a method for purifying reclaimedpolystyrene includes dissolving polystyrene in n-butane at a masspercent concentration of at least 0.5%. In another embodiment, thepolystyrene is dissolved at a mass percent concentration of at least 1%.In another embodiment, the polystyrene is dissolved at a mass percentconcentration of at least 2%. In another embodiment, the polystyrene isdissolved at a mass percent concentration of at least 3%. In anotherembodiment, the polystyrene is dissolved at a mass percent concentrationof at least 4%. In another embodiment, the polystyrene is dissolved at amass percent concentration of at least 5%. In another embodiment, amethod for purifying reclaimed polystyrene includes dissolvingpolystyrene in n-butane at a mass percent concentration up to 20%. Inanother embodiment, the polystyrene is dissolved at a mass percentconcentration up to 18%. In another embodiment, the polystyrene isdissolved at a mass percent concentration up to 16%. In anotherembodiment, the polystyrene is dissolved at a mass percent concentrationup to 14%. In another embodiment, the polystyrene is dissolved at a masspercent concentration up to 12%.

In one embodiment, a method for purifying reclaimed polymers includesdissolving poly(dimethylsiloxane) in a fluid solvent at a temperatureand a pressure wherein the poly(dimethylsiloxane) is dissolved in thefluid solvent. In another embodiment, a method for purifying reclaimedpolymers includes dissolving poly(dimethylsiloxane) in n-butane at atemperature from about 115° C. to about 280° C. In another embodiment, amethod for purifying reclaimed polymers includes dissolvingpoly(dimethylsiloxane) in n-butane at a temperature from about 120° C.to about 220° C. In another embodiment, a method for purifying reclaimedpolymers includes dissolving poly(dimethylsiloxane) in n-butane at atemperature from about 140° C. to about 180° C. In another embodiment, amethod for purifying reclaimed polymers includes dissolvingpoly(dimethylsiloxane) in n-butane at a pressure from about 500 psig(3.45 MPa) to about 2,100 psig (14.48 MPa). In another embodiment, amethod for purifying reclaimed polymers includes dissolvingpoly(dimethylsiloxane) in n-butane at a pressure from about 700 psig(4.83 MPa) to about 1,400 psig (9.65 MPa). In another embodiment, amethod for purifying reclaimed polymers includes dissolvingpoly(dimethylsiloxane) in n-butane at a pressure from about 800 psig(5.52 MPa) to about 1,300 psig (8.96 MPa). In another embodiment, amethod for purifying reclaimed poly(dimethylsiloxane) includesdissolving poly(dimethylsiloxane) in n-butane at a mass percentconcentration of at least 0.5%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration ofat least 1%. In another embodiment, the poly(dimethylsiloxane) isdissolved at a mass percent concentration of at least 2%. In anotherembodiment, the poly(dimethylsiloxane) is dissolved at a mass percentconcentration of at least 3%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration ofat least 4%. In another embodiment, the poly(dimethylsiloxane) isdissolved at a mass percent concentration of at least 5%. In anotherembodiment, a method for purifying reclaimed poly(dimethylsiloxane)includes dissolving poly(dimethylsiloxane) in n-butane at a mass percentconcentration up to 20%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration upto 18%. In another embodiment, the poly(dimethylsiloxane) is dissolvedat a mass percent concentration up to 16%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration upto 14%. In another embodiment, the poly(dimethylsiloxane) is dissolvedat a mass percent concentration up to 12%.

Sedimentation

In one embodiment of the present invention, a method for purifyingpolymers includes separating the undissolved contaminants from thepolymer solution via a sedimentation (also known as settling) step at atemperature and at a pressure wherein the polymer remains dissolved inthe fluid solvent. In one embodiment, the settling step causes theundissolved contaminants to experience a force that uniformly moves theundissolved contaminants in the direction of the force. Typically theapplied settling force is gravity, but can also be a centrifugal,centripetal, or some other force. The amount of applied force andduration of settling time will depend upon several parameters,including, but not limited to: particle size of the contaminantparticles, contaminant particle densities, density of the fluid orsolution, and the viscosity of the fluid or solution. The followingequation (equation 2) is a relationship between the aforementionedparameters and the settling velocity, which is a measure of thecontaminant sedimentation rate:

$\begin{matrix}{v = \frac{2\left( {\rho_{p} - \rho_{f}} \right)g\; r^{2}}{9\eta}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

where ν is the settling velocity, ρ_(p) is the density of thecontaminant particle, ρ_(f) is the density of the fluid or solution, gis the acceleration due to the applied force (typically gravity), r isthe radius of the contaminant particle and η is the dynamic viscosity ofthe fluid or solution. Some of the key parameters that determine thesolution viscosity are: the chemical composition of the fluid solvent,the molecular weight of the polymer dissolved in the fluid solvent, theconcentration of dissolved polymer in the fluid solvent, the temperatureof the fluid solvent solution, and the pressure of the fluid solventsolution.

In one embodiment, a method for purifying reclaimed polymers includessettling contaminants from a polyethylene/fluid solvent solution at atemperature and at a pressure wherein the polyethylene remains dissolvedin the fluid solvent. In another embodiment, a method for purifyingreclaimed polymers includes settling contaminants from apolyethylene/fluid solvent solution at a temperature from about 90° C.to about 280° C. In yet another embodiment, a method for purifyingreclaimed polymers includes settling contaminants from apolyethylene/fluid solvent solution at a temperature from about 110° C.to about 220° C. In one embodiment, a method for purifying reclaimedpolymers includes settling contaminants from a polyethylene/fluidsolvent solution at a pressure from about 200 psig (1.38 MPa) to about9,000 psig (62.05 MPa). In another embodiment, a method for purifyingreclaimed polymers includes settling contaminants from apolyethylene/fluid solvent solution at a pressure from about 400 psig(2.76 MPa) to about 2,600 psig (17.93 MPa).

In another embodiment, a method for purifying reclaimed polymersincludes settling contaminants from a polyethylene/n-butane solution ata temperature from about 90° C. to about 280° C. In another embodiment,a method for purifying reclaimed polymers includes settling contaminantsfrom a polyethylene/n-butane solution at a temperature from about 100°C. to about 220° C. In another embodiment, a method for purifyingreclaimed polymers includes settling contaminants from apolyethylene/n-butane solution at a temperature from about 130° C. toabout 180° C. In another embodiment, a method for purifying reclaimedpolymers includes settling contaminants from a polyethylene/n-butanesolution at a pressure from about 4,000 psig (27.58 MPa) to about 8,000psig (55.16 MPa). In another embodiment, a method for purifyingreclaimed polymers includes settling contaminants from apolyethylene/n-butane solution at a pressure about 4,200 psig (28.96MPa) to about 7,000 psig (48.26 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes settling contaminants from apolyethylene/n-butane solution at a pressure from about 4,500 psig(31.03 MPa) to about 6,000 psig (41.37 MPa). In another embodiment, amethod for purifying reclaimed polymers includes settling contaminantsfrom a polyethylene/n-butane solution wherein the polyethylene isdissolved at a mass percent concentration of at least 0.5%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration of at least 1%. In another embodiment, the polyethylene isdissolved at a mass percent concentration of at least 2%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration of at least 3%. In another embodiment, the polyethylene isdissolved at a mass percent concentration of at least 4%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration of at least 5%. In another embodiment, a method forpurifying reclaimed polymers includes settling contaminants from apolyethylene/n-butane solution where in the polyethylene is dissolved ata mass percent concentration up to 20%. In another embodiment, thepolyethylene is dissolved at a mass percent concentration up to 18%. Inanother embodiment, the polyethylene is dissolved at a mass percentconcentration up to 16%. In another embodiment, the polyethylene isdissolved at a mass percent concentration up to 14%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration up to 12%.

In another embodiment, a method for purifying reclaimed polymersincludes settling contaminants from a polyethylene/n-pentane solution ata temperature from about 90° C. to about 280° C. In another embodiment,a method for purifying reclaimed polymers includes settling contaminantsfrom a polyethylene/n-pentane solution at a temperature from about 100°C. to about 220° C. In another embodiment, a method for purifyingreclaimed polymers includes settling contaminants from apolyethylene/n-pentane solution at a temperature from about 130° C. toabout 180° C. In another embodiment, a method for purifying reclaimedpolymers includes settling contaminants from a polyethylene/n-pentanesolution at a pressure from about 800 psig (5.52 MPa) to about 3,000psig (20.68 MPa). In another embodiment, a method for purifyingreclaimed polymers includes settling contaminants from apolyethylene/n-pentane solution at a pressure from about 900 psig (6.21MPa) to about 3,000 psig (20.68 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes settling contaminants from apolyethylene/n-pentane solution at a pressure from about 1,000 psig(6.89 MPa) to about 2,400 psig (16.55 MPa). In another embodiment, amethod for purifying reclaimed polymers includes settling contaminantsfrom a polyethylene/n-pentane solution wherein the polyethylene isdissolved at a mass percent concentration of at least 0.5%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration of at least 1%. In another embodiment, the polyethylene isdissolved at a mass percent concentration of at least 2%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration of at least 3%. In another embodiment, the polyethylene isdissolved at a mass percent concentration of at least 4%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration of at least 5%. In another embodiment, a method forpurifying reclaimed polymers includes settling contaminants from apolyethylene/n-pentane solution where in the polyethylene is dissolvedat a mass percent concentration up to 20%. In another embodiment, thepolyethylene is dissolved at a mass percent concentration up to 18%. Inanother embodiment, the polyethylene is dissolved at a mass percentconcentration up to 16%. In another embodiment, the polyethylene isdissolved at a mass percent concentration up to 14%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration up to 12%.

In one embodiment, a method for purifying reclaimed polymers includessettling contaminants from a polypropylene/fluid solvent solution at atemperature and at a pressure wherein the polypropylene remainsdissolved in the fluid solvent. In another embodiment, a method forpurifying reclaimed polymers includes settling contaminants from apolypropylene/n-butane solution at a temperature from about 90° C. toabout 280° C. In another embodiment, a method for purifying reclaimedpolymers includes settling contaminants from a polypropylene/n-butanesolution at a temperature from about 100° C. to about 220° C. In anotherembodiment, a method for purifying reclaimed polymers includes settlingcontaminants from a polypropylene/n-butane solution at a temperaturefrom about 130° C. to about 180° C. In another embodiment, a method forpurifying reclaimed polymers includes settling contaminants from apolypropylene/n-butane solution at a pressure from about 350 psig (2.41MPa) to about 4,000 psig (27.57 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes settling contaminants from apolypropylene/n-butane solution at a pressure from about 1,000 psig(6.89 MPa) to about 3,500 psig (24.13 MPa). In another embodiment, amethod for purifying reclaimed polymers includes settling contaminantsfrom a polypropylene/n-butane solution at a pressure from about 2,000psig (13.79 MPa) to about 3,000 psig (20.68 MPa). In another embodiment,a method for purifying reclaimed polymers includes settling contaminantsfrom a polypropylene/n-butane solution wherein the polypropylene isdissolved at a mass percent concentration of at least 0.5%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration of at least 1%. In another embodiment, the polypropyleneis dissolved at a mass percent concentration of at least 2%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration of at least 3%. In another embodiment, the polypropyleneis dissolved at a mass percent concentration of at least 4%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration of at least 5%. In another embodiment, a method forpurifying reclaimed polymers includes settling contaminants from apolypropylene/n-butane solution where in the polypropylene is dissolvedat a mass percent concentration up to 20%. In another embodiment, thepolypropylene is dissolved at a mass percent concentration up to 18%. Inanother embodiment, the polypropylene is dissolved at a mass percentconcentration up to 16%. In another embodiment, the polypropylene isdissolved at a mass percent concentration up to 14%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration up to 12%.

In another embodiment, a method for purifying reclaimed polymersincludes settling contaminants from a polypropylene/propane solution ata temperature from about 90° C. to about 280° C. In another embodiment,a method for purifying reclaimed polymers includes settling contaminantsfrom a polypropylene/propane solution at a temperature from about 100°C. to about 220° C. In another embodiment, a method for purifyingreclaimed polymers includes settling contaminants from apolypropylene/propane solution at a temperature from about 130° C. toabout 180° C. In another embodiment, a method for purifying reclaimedpolymers includes settling contaminants from a polypropylene/propanesolution at a pressure from about 2,000 psig (13.79 MPa) to about 8,000psig (55.16 MPa). In another embodiment, a method for purifyingreclaimed polymers includes settling contaminants from apolypropylene/propane solution at a pressure from about 3,000 psig(20.68 MPa) to about 6,000 psig (41.37 MPa). In another embodiment, amethod for purifying reclaimed polymers includes settling contaminantsfrom a polypropylene/propane solution at a pressure from about 3,500psig (24.13 MPa) to about 5,000 psig (34.47 MPa). In another embodiment,a method for purifying reclaimed polymers includes settling contaminantsfrom a polypropylene/propane solution wherein the polypropylene isdissolved at a mass percent concentration of at least 0.5%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration of at least 1%. In another embodiment, the polypropyleneis dissolved at a mass percent concentration of at least 2%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration of at least 3%. In another embodiment, the polypropyleneis dissolved at a mass percent concentration of at least 4%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration of at least 5%. In another embodiment, a method forpurifying reclaimed polymers includes settling contaminants from apolypropylene/propane solution where in the polypropylene is dissolvedat a mass percent concentration up to 20%. In another embodiment, thepolypropylene is dissolved at a mass percent concentration up to 18%. Inanother embodiment, the polypropylene is dissolved at a mass percentconcentration up to 16%. In another embodiment, the polypropylene isdissolved at a mass percent concentration up to 14%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration up to 12%.

In one embodiment, a method for purifying reclaimed polymers includessettling contaminants from a polystyrene/fluid solvent solution at atemperature and at a pressure wherein the polystyrene remains dissolvedin the fluid solvent. In another embodiment, a method for purifyingreclaimed polymers includes settling contaminants from apolystyrene/n-butane solution at a temperature from about 90° C. toabout 280° C. In another embodiment, a method for purifying reclaimedpolymers includes settling contaminants from a polystyrene/n-butanesolution at a temperature from about 100° C. to about 220° C. In anotherembodiment, a method for purifying reclaimed polymers includes settlingcontaminants from a polystyrene/n-butane solution at a temperature fromabout 130° C. to about 180° C. In another embodiment, a method forpurifying reclaimed polymers includes settling contaminants from apolystyrene/n-butane solution at a pressure from about 1,000 psig (6.89MPa) to about 9,000 psig (62.05 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes settling contaminants from apolystyrene/n-butane solution at a pressure from about 2,000 psig (13.79MPa) to about 8,000 psig (55.16 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes settling contaminants from apolystyrene/n-butane solution at a pressure from about 4,500 psig (31.03MPa) to about 7,500 psig (51.71 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes settling contaminants from apolystyrene/n-butane solution wherein the polystyrene is dissolved at amass percent concentration of at least 0.5%. In another embodiment, thepolystyrene is dissolved at a mass percent concentration of at least 1%.In another embodiment, the polystyrene is dissolved at a mass percentconcentration of at least 2%. In another embodiment, the polystyrene isdissolved at a mass percent concentration of at least 3%. In anotherembodiment, the polystyrene is dissolved at a mass percent concentrationof at least 4%. In another embodiment, the polystyrene is dissolved at amass percent concentration of at least 5%. In another embodiment, amethod for purifying reclaimed polymers includes settling contaminantsfrom a polystyrene/n-butane solution where in the polystyrene isdissolved at a mass percent concentration up to 20%. In anotherembodiment, the polystyrene is dissolved at a mass percent concentrationup to 18%. In another embodiment, the polystyrene is dissolved at a masspercent concentration up to 16%. In another embodiment, the polystyreneis dissolved at a mass percent concentration up to 14%. In anotherembodiment, the polystyrene is dissolved at a mass percent concentrationup to 12%.

In one embodiment, a method for purifying reclaimed polymers includessettling contaminants from a poly(dimethylsiloxane)/fluid solventsolution at a temperature and at a pressure wherein thepoly(dimethylsiloxane) remains dissolved in the fluid solvent. Inanother embodiment, a method for purifying reclaimed polymers includessettling contaminants from a poly(dimethylsiloxane)/n-butane solution ata temperature from about 115° C. to about 280° C. In another embodiment,a method for purifying reclaimed polymers includes settling contaminantsfrom a poly(dimethylsiloxane)/n-butane solution at a temperature fromabout 120° C. to about 220° C. In another embodiment, a method forpurifying reclaimed polymers includes settling contaminants from apoly(dimethylsiloxane)/n-butane solution at a temperature from about140° C. to about 180° C. In another embodiment, a method for purifyingreclaimed polymers includes settling contaminants from apoly(dimethylsiloxane)/n-butane solution at a pressure from about 500psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In another embodiment,a method for purifying reclaimed polymers includes settling contaminantsfrom a poly(dimethylsiloxane)/n-butane solution at a pressure from about700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa). In anotherembodiment, a method for purifying reclaimed polymers includes settlingcontaminants from a poly(dimethylsiloxane)/n-butane solution with solidmedia at a pressure from about 800 psig (5.52 MPa) to about 1,300 psig(8.96 MPa). In another embodiment, a method for purifying reclaimedpolymers includes settling contaminants from apoly(dimethylsiloxane)/n-butane solution wherein thepoly(dimethylsiloxane) is dissolved at a mass percent concentration ofat least 0.5%. In another embodiment, the poly(dimethylsiloxane) isdissolved at a mass percent concentration of at least 1%. In anotherembodiment, the poly(dimethylsiloxane) is dissolved at a mass percentconcentration of at least 2%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration ofat least 3%. In another embodiment, the poly(dimethylsiloxane) isdissolved at a mass percent concentration of at least 4%. In anotherembodiment, the poly(dimethylsiloxane) is dissolved at a mass percentconcentration of at least 5%. In another embodiment, a method forpurifying reclaimed polymers includes settling contaminants from apoly(dimethylsiloxane)/n-butane solution where in thepoly(dimethylsiloxane) is dissolved at a mass percent concentration upto 20%. In another embodiment, the poly(dimethylsiloxane) is dissolvedat a mass percent concentration up to 18%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration upto 16%. In another embodiment, the poly(dimethylsiloxane) is dissolvedat a mass percent concentration up to 14%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration upto 12%.

Filtration

A typical filtration system comprises a filter medium, a filtercontainer, a filter inlet, and a filter outlet. The filter mediumcomprises filter particles that are contained within the filtercontainer. The filter inlet is in fluid communication with the filtercontainer and carries the filtration feed stream in the filtercontainer, and the filter outlet is in fluid communication with thefiltration system and carries the filtrate stream out of the filtercontainer. A filtration system can comprise one or more filter media,filter containers, and filter inlets and outlets in series or inparallel. Also, a filtration system can operate in radial or axial flow,or it can operate in upflow, downflow, or crossflow. A non-limitingexample of a radial flow filter is a candle filter. Furthermore, thefiltration can be of surface or depth filtration type, and is based onmechanical mode of cation.

The filter medium used in depth filtration comprises an aggregate offilter particles, which can be either homogeneous or heterogeneous. Thefilter particles can be uniformly or non-uniformly distributed (e.g.,layers of different filter particles) within the filter medium. Thefilter particles forming the filter medium also need not be identical inshape or size and may be provided in either a loose or interconnectedform. For example, a filter medium might comprise filter particles whichcan be either in loose association, or partially or wholly bonded by apolymeric binder or other means to form an integral structure.

Also, the filter particles can be provided in a variety of shapes andsizes. For example, and not by way of limitation, the filter particlescan be provided in simple forms, such as powder, granules, fibers, andbeads. The filter particles can be provided in the shape of a sphere,polyhedron, cylinder, as well as other symmetrical, asymmetrical, andirregular shapes. Further, the filter particles can also be formed intocomplex forms such as webs, screens, meshes, non-wovens, wovens, andbonded blocks, which may or may not be formed from the simple formsdescribed above.

The filter particles can vary in size, from impalpable filter particles(e.g., a very fine powder) to palpable filter particles. Furthermore,the size of the filter particles need not be uniform among the filterparticles which are used in any single filtration system. In fact, itcan be desirable to provide filter particles having different sizes in asingle filter.

In one embodiment of the present invention, the size of the filterparticles varies between about 0.1 mm and about 10 mm. In anotherembodiment of the present invention, the size of the filter particlesvaries between about 10 mm and about 8 mm. In yet another embodiment ofthe present invention, the size of the filter particles varies betweenabout 100 mm and about 5 mm. In even yet another embodiment of thepresent invention, the size of the filter particles varies between about1 mm and about 4 mm. In one embodiment of the present invention, thesize of the filter particles varies between about 10 μm and about 100μm. For spherical and cylindrical particles (e.g., fibers, beads, etc.),the above-described dimensions refer to the diameter of the filterparticles. For filter particles having substantially different shapes,the above-described dimensions refer to the largest dimension (e.g.length, width, or height).

A non-limiting example of a mechanical mode of action is size exclusion,where a suspended (dispersed) contaminant gets retained by thefiltration medium, and thus separated from the filtration feed stream,because the suspended contaminant's size is larger than the pores of thefiltration medium. As described, size exclusion is an inter-particlephenomenon.

Non-limiting examples of filter particles are silicon oxide (silica),silica gel, aluminum oxide (alumina), activated alumina, iron oxide,aluminum silicate, magnesium silicate, amorphous volcanic glass,reclaimed glass, sand, quartz, diatomaceous earth, zeolite, molecularsieve, perlite, clay, fuller's earth, bentonite clay, metal organicframework (MOF), covalent organic framework (COF), zeolitic imidazolateframework (ZIF), cellulose, lignocellulose, anthracite coal, carbonblack, coke, and activated carbon. In one embodiment of the presentinvention, the filter particles are selected from the group consistingof silica, activated alumina, silica gel, volcanic glass, fuller'searth, bentonite clay, and mixtures thereof. In another embodiment ofthe present invention, the filter particles are selected from the groupconsisting of activated carbon, activated alumina, diatomaceous earth,and mixtures thereof. In yet another embodiment of the presentinvention, the filter particles are selected from the group consistingof MOF, COF, ZIF, activated carbon, activated alumina, and mixturesthereof. In even yet another embodiment of the present invention, thefilter particles are selected from the group consisting of diatomaceousearth, activated alumina, and mixtures thereof.

Non-limiting examples of filter media used in surface filtration are athin layer of filter particles, porous ceramics, filter paper, filtercloths, plastic membrane, screen, non-woven, woven, porous frit/sinteredmetal, and perforated plate. In a typical surface filtration, theretained contaminants form a cake on top of the filter medium thatincreases in thickness as the filtration proceeds. Typically, after acertain filtration time, the filter cake needs to be removed, as itoffers unsustainable pressure drop, either by mechanical action orback-flushing. In one embodiment of the present invention, the filtermedium used in surface filtration is selected from the group consistingof a thin layer of diatomaceous earth particles deposited onto a wovenmetal porous core (typically called sock). The porous core supports thefilter medium and allows the filtration feed stream to flow through.Non-limiting examples of cores are perforated tubes and screen sleeves.

Filter aids may be used in filtration. Non-limiting examples of filteraids are diatomaceous earth (also called kieselguhr), cellulose, andperlite. These filter aids can be used either as a pre-coat to thefilter media or added into the filtration feed stream. In the lattercase (also called body feed), the filter aids increase the porosity ofthe cake formed onto the filter media thus reducing the pressure dropthrough the cake during filtration.

At the end of their useful life, filters can either be removed from theoperation and get replaced with fresh ones, or get regenerated.Non-limiting examples of regeneration are back-flushing, thermalregeneration, and solvent regeneration.

In one embodiment of the present invention, the surface filter comprisesa candle filter. In another embodiment of the present invention, thecandle filter comprises a thin layer of diatomaceous earth depositedonto a woven metal porous core. In yet another embodiment of the presentinvention, the thickness of the diatomaceous earth layer is betweenabout 1 mm and about 20 mm. In even yet another embodiment of thepresent invention, the thickness of the diatomaceous earth layer isbetween about 2 mm and about 10 mm. In one embodiment of the presentinvention, the thickness of the diatomaceous earth layer is betweenabout 3 mm and about 5 mm.

The permeability of the filter medium is measured (as it is well knownto those skilled in the art) by passing a fluid stream through thefilter medium and measuring the flow rate and pressure drop. The unit ofmeasurement is millidarcy (mD), and 1 mD is equivalent to the passage of1 mL of fluid with 1 mPa·s (1 cP) viscosity, flowing in 1 s under apressure of 1 atm, through a filter medium 1 cm² in cross-sectional areaand 1 cm in thickness. In one embodiment of the present invention, thepermeability of the diatomaceous earth medium is between about 30 mD andabout 20,000 mD. In another embodiment of the present invention, thepermeability of the diatomaceous earth medium is between about 400 mDand about 8,000 mD. In even another embodiment of the present invention,the permeability of the diatomaceous earth medium is between about 1,000mD and about 4,000 mD. In even yet another embodiment of the presentinvention, the permeability of the diatomaceous earth medium is betweenabout 2,300 mD and about 3,400 mD.

In another embodiment of the present invention, the diatomaceous earthmedium retains suspended particles with diameter larger than about 0.3μm. In yet another embodiment of the present invention, the diatomaceousearth medium retains suspended particles with diameter larger than about0.8 μm. In even yet another embodiment of the present invention, thediatomaceous earth medium retains suspended particles with diameterlarger than about 1 μm. In one embodiment of the present invention, thediatomaceous earth medium retains suspended particles with diameterlarger than about 1.7 μm. In another embodiment of the presentinvention, the diatomaceous earth medium retains suspended particleswith diameter larger than about 4 μm.

In one embodiment of the present invention, the candle filter comprisesa thin a diatomaceous earth medium deposited on a woven metal core;wherein the thickness of the diatomaceous earth medium is between about2 mm and about 10 mm; wherein the permeability of the diatomaceous earthmedium is between about 2,300 mD and 3,400 mD; and wherein thediatomaceous earth medium retains suspended particles with diameterlarger than about 1.7 μm.

In one embodiment, a method for purifying reclaimed polymers includesfiltering contaminants from a polyethylene/fluid solvent solution at atemperature and at a pressure wherein the polyethylene remains dissolvedin the fluid solvent. In another embodiment, a method for purifyingreclaimed polymers includes filtering contaminants from apolyethylene/fluid solvent solution at a temperature from about 90° C.to about 280° C. In yet another embodiment, a method for purifyingreclaimed polymers includes filtering contaminants from apolyethylene/fluid solvent solution at a temperature from about 110° C.to about 220° C. In one embodiment, a method for purifying reclaimedpolymers includes filtering contaminants from a polyethylene/fluidsolvent solution at a pressure from about 200 psig (1.38 MPa) to about9,000 psig (62.05 MPa). In another embodiment, a method for purifyingreclaimed polymers includes filtering contaminants from apolyethylene/fluid solvent solution at a pressure from about 400 psig(2.76 MPa) to about 2,600 psig (17.93 MPa).

In one embodiment, a method for purifying reclaimed polymers includesfiltering contaminants from a polyethylene/n-butane solution at atemperature from about 90° C. to about 280° C. In another embodiment, amethod for purifying reclaimed polymers includes filtering contaminantsfrom a polyethylene/n-butane solution at a temperature from about 100°C. to about 220° C. In yet another embodiment, a method for purifyingreclaimed polymers includes filtering contaminants from apolyethylene/n-butane solution at a temperature from about 130° C. toabout 180° C. In one embodiment, a method for purifying reclaimedpolymers includes filtering contaminants from a polyethylene/n-butanesolution at a pressure from about 4000 psig (27.58 MPa) to about 8,000psig (55.16 MPa). In another embodiment, a method for purifyingreclaimed polymers includes filtering contaminants from apolyethylene/n-butane solution at a pressure from about 4,200 psig(28.96 MPa) to about 7,000 psig (48.26 MPa). In yet another embodiment,a method for purifying reclaimed polymers includes filteringcontaminants from a polyethylene/n-butane solution at a pressure fromabout 4,500 psig (31.03 MPa) to about 6,000 psig (41.37 MPa). In oneembodiment, a method for purifying reclaimed polymers includes filteringcontaminants from a polyethylene/n-butane solution wherein thepolyethylene is dissolved at a mass percent concentration of at least0.5%. In another embodiment, the polyethylene is dissolved at a masspercent concentration of at least 1%. In yet another embodiment, thepolyethylene is dissolved at a mass percent concentration of at least2%. In even yet another embodiment, the polyethylene is dissolved at amass percent concentration of at least 3%. In one embodiment, thepolyethylene is dissolved at a mass percent concentration of at least4%. In another embodiment, the polyethylene is dissolved at a masspercent concentration of at least 5%. In yet another embodiment, amethod for purifying reclaimed polymers includes filtering contaminantsfrom a polyethylene/n-butane solution where in the polyethylene isdissolved at a mass percent concentration up to 20%. In even yet anotherembodiment, the polyethylene is dissolved at a mass percentconcentration up to 18%. In one embodiment, the polyethylene isdissolved at a mass percent concentration up to 16%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration up to 14%. In yet another embodiment, the polyethylene isdissolved at a mass percent concentration up to 12%.

In another embodiment, a method for purifying reclaimed polymersincludes filtering contaminants from a polyethylene/n-pentane solutionat a temperature from about 90° C. to about 280° C. In anotherembodiment, a method for purifying reclaimed polymers includes filteringcontaminants from a polyethylene/n-pentane solution at a temperaturefrom about 100° C. to about 220° C. In another embodiment, a method forpurifying reclaimed polymers includes filtering contaminants from apolyethylene/n-pentane solution at a temperature from about 130° C. toabout 180° C. In another embodiment, a method for purifying reclaimedpolymers includes filtering contaminants from a polyethylene/n-pentanesolution at a pressure from about 800 psig (5.52 MPa) to about 4,000psig (27.58 MPa). In another embodiment, a method for purifyingreclaimed polymers includes filtering contaminants from apolyethylene/n-pentane solution at a pressure from about 900 psig (6.21MPa) to about 3,000 psig (20.68 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes filtering contaminants from apolyethylene/n-pentane solution at a pressure from about 1,000 psig(6.89 MPa) to about 2,400 psig (16.55 MPa). In another embodiment, amethod for purifying reclaimed polymers includes filtering contaminantsfrom a polyethylene/n-pentane solution wherein the polyethylene isdissolved at a mass percent concentration of at least 0.5%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration of at least 1%. In another embodiment, the polyethylene isdissolved at a mass percent concentration of at least 2%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration of at least 3%. In another embodiment, the polyethylene isdissolved at a mass percent concentration of at least 4%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration of at least 5%. In another embodiment, a method forpurifying reclaimed polymers includes filtering contaminants from apolyethylene/n-pentane solution where in the polyethylene is dissolvedat a mass percent concentration up to 20%. In another embodiment, thepolyethylene is dissolved at a mass percent concentration up to 18%. Inanother embodiment, the polyethylene is dissolved at a mass percentconcentration up to 16%. In another embodiment, the polyethylene isdissolved at a mass percent concentration up to 14%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration up to 12%.

In one embodiment, a method for purifying reclaimed polymers includesfiltering contaminants from a polypropylene/n-butane solution at atemperature from about 90° C. to about 280° C. In another embodiment, amethod for purifying reclaimed polymers includes filtering contaminantsfrom a polypropylene/n-butane solution at a temperature from about 100°C. to about 220° C. In yet another embodiment, a method for purifyingreclaimed polymers includes filtering contaminants from apolypropylene/n-butane solution at a temperature from about 130° C. toabout 180° C. In one embodiment, a method for purifying reclaimedpolymers includes filtering contaminants from a polypropylene/n-butanesolution at a pressure from about 350 psig (2.41 MPa) to about 4,000psig (27.57 MPa). In another embodiment, a method for purifyingreclaimed polymers includes filtering contaminants from apolypropylene/n-butane solution at a pressure from about 1,000 psig(6.89 MPa) to about 3,500 psig (24.13 MPa). In yet another embodiment, amethod for purifying reclaimed polymers includes filtering contaminantsfrom a polypropylene/n-butane solution at a pressure from about 2,000psig (13.79 MPa) to about 3,000 psig (20.68 MPa). In one embodiment, amethod for purifying reclaimed polymers includes filtering contaminantsfrom a polypropylene/n-butane solution wherein the polypropylene isdissolved at a mass percent concentration of at least 0.5%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration of at least 1%. In yet another embodiment, thepolypropylene is dissolved at a mass percent concentration of at least2%. In even yet another embodiment, the polypropylene is dissolved at amass percent concentration of at least 3%. In one embodiment, thepolypropylene is dissolved at a mass percent concentration of at least4%. In another embodiment, the polypropylene is dissolved at a masspercent concentration of at least 5%. In yet another embodiment, amethod for purifying reclaimed polymers includes filtering contaminantsfrom a polypropylene/n-butane solution where in the polypropylene isdissolved at a mass percent concentration up to 20%. In even yet anotherembodiment, the polypropylene is dissolved at a mass percentconcentration up to 18%. In one embodiment, the polypropylene isdissolved at a mass percent concentration up to 16%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration up to 14%. In yet another embodiment, the polypropylene isdissolved at a mass percent concentration up to 12%.

In another embodiment, a method for purifying reclaimed polymersincludes filtering contaminants from a polypropylene/propane solution ata temperature from about 90° C. to about 280° C. In another embodiment,a method for purifying reclaimed polymers includes filteringcontaminants from a polypropylene/propane solution at a temperature fromabout 100° C. to about 220° C. In another embodiment, a method forpurifying reclaimed polymers includes filtering contaminants from apolypropylene/propane solution at a temperature from about 130° C. toabout 180° C. In another embodiment, a method for purifying reclaimedpolymers includes filtering contaminants from a polypropylene/propanesolution at a pressure from about 2,000 psig (13.79 MPa) to about 8,000psig (55.16 MPa). In another embodiment, a method for purifyingreclaimed polymers includes filtering contaminants from apolypropylene/propane solution at a pressure from about 3,000 psig(20.68 MPa) to about 6,000 psig (41.37 MPa). In another embodiment, amethod for purifying reclaimed polymers includes filtering contaminantsfrom a polypropylene/propane solution at a pressure from about 3,500psig (24.13 MPa) to about 5,000 psig (34.47 MPa). In another embodiment,a method for purifying reclaimed polymers includes filteringcontaminants from a polypropylene/propane solution wherein thepolypropylene is dissolved at a mass percent concentration of at least0.5%. In another embodiment, the polypropylene is dissolved at a masspercent concentration of at least 1%. In another embodiment, thepolypropylene is dissolved at a mass percent concentration of at least2%. In another embodiment, the polypropylene is dissolved at a masspercent concentration of at least 3%. In another embodiment, thepolypropylene is dissolved at a mass percent concentration of at least4%. In another embodiment, the polypropylene is dissolved at a masspercent concentration of at least 5%. In another embodiment, a methodfor purifying reclaimed polymers includes filtering contaminants from apolypropylene/propane solution where in the polypropylene is dissolvedat a mass percent concentration up to 20%. In another embodiment, thepolypropylene is dissolved at a mass percent concentration up to 18%. Inanother embodiment, the polypropylene is dissolved at a mass percentconcentration up to 16%. In another embodiment, the polypropylene isdissolved at a mass percent concentration up to 14%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration up to 12%.

In one embodiment, a method for purifying reclaimed polymers includesfiltering contaminants from a polystyrene/fluid solvent solution at atemperature and at a pressure wherein the polystyrene remains dissolvedin the fluid solvent. In another embodiment, a method for purifyingreclaimed polymers includes filtering contaminants from apolystyrene/n-butane solution at a temperature from about 90° C. toabout 280° C. In another embodiment, a method for purifying reclaimedpolymers includes filtering contaminants from a polystyrene/n-butanesolution at a temperature from about 100° C. to about 220° C. In anotherembodiment, a method for purifying reclaimed polymers includes filteringcontaminants from a polystyrene/n-butane solution at a temperature fromabout 130° C. to about 180° C. In another embodiment, a method forpurifying reclaimed polymers includes filtering contaminants from apolystyrene/n-butane solution at a pressure from about 1,000 psig (6.89MPa) to about 9,000 psig (62.05 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes filtering contaminants from apolystyrene/n-butane solution at a pressure from about 2,000 psig (13.79MPa) to about 8,000 psig (55.16 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes filtering contaminants from apolystyrene/n-butane solution at a pressure from about 4,500 psig (31.03MPa) to about 7,500 psig (51.71 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes filtering contaminants from apolystyrene/n-butane solution wherein the polystyrene is dissolved at amass percent concentration of at least 0.5%. In another embodiment, thepolystyrene is dissolved at a mass percent concentration of at least 1%.In another embodiment, the polystyrene is dissolved at a mass percentconcentration of at least 2%. In another embodiment, the polystyrene isdissolved at a mass percent concentration of at least 3%. In anotherembodiment, the polystyrene is dissolved at a mass percent concentrationof at least 4%. In another embodiment, the polystyrene is dissolved at amass percent concentration of at least 5%. In another embodiment, amethod for purifying reclaimed polymers includes filtering contaminantsfrom a polystyrene/n-butane solution wherein the polystyrene isdissolved at a mass percent concentration up to 20%. In anotherembodiment, the polystyrene is dissolved at a mass percent concentrationup to 18%. In another embodiment, the polystyrene is dissolved at a masspercent concentration up to 16%. In another embodiment, the polystyreneis dissolved at a mass percent concentration up to 14%. In anotherembodiment, the polystyrene is dissolved at a mass percent concentrationup to 12%.

In one embodiment, a method for purifying reclaimed polymers includesfiltering contaminants from a poly(dimethylsiloxane)/fluid solventsolution at a temperature and at a pressure wherein thepoly(dimethylsiloxane) remains dissolved in the fluid solvent. Inanother embodiment, a method for purifying reclaimed polymers includesfiltering contaminants from a poly(dimethylsiloxane)/n-butane solutionat a temperature from about 115° C. to about 280° C. In anotherembodiment, a method for purifying reclaimed polymers includes filteringcontaminants from a poly(dimethylsiloxane)/n-butane solution at atemperature from about 120° C. to about 220° C. In another embodiment, amethod for purifying reclaimed polymers includes filtering contaminantsfrom a poly(dimethylsiloxane)/n-butane solution at a temperature fromabout 140° C. to about 180° C. In another embodiment, a method forpurifying reclaimed polymers includes filtering contaminants from apoly(dimethylsiloxane)/n-butane solution at a pressure from about 500psig (3.45 MPa) to about 2,100 psig (14.48 MPa). In another embodiment,a method for purifying reclaimed polymers includes filteringcontaminants from a poly(dimethylsiloxane)/n-butane solution at apressure from about 700 psig (4.83 MPa) to about 1,400 psig (9.65 MPa).In another embodiment, a method for purifying reclaimed polymersincludes filtering contaminants from a poly(dimethylsiloxane)/n-butanesolution at a pressure from about 800 psig (5.52 MPa) to about 1,300psig (8.96 MPa). In another embodiment, a method for purifying reclaimedpolymers includes filtering contaminants from apoly(dimethylsiloxane)/n-butane solution wherein thepoly(dimethylsiloxane) is dissolved at a mass percent concentration ofat least 0.5%. In another embodiment, the poly(dimethylsiloxane) isdissolved at a mass percent concentration of at least 1%. In anotherembodiment, the poly(dimethylsiloxane) is dissolved at a mass percentconcentration of at least 2%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration ofat least 3%. In another embodiment, the poly(dimethylsiloxane) isdissolved at a mass percent concentration of at least 4%. In anotherembodiment, the poly(dimethylsiloxane) is dissolved at a mass percentconcentration of at least 5%. In another embodiment, a method forpurifying reclaimed polymers includes filtering contaminants from apoly(dimethylsiloxane)/n-butane solution wherein thepoly(dimethylsiloxane) is dissolved at a mass percent concentration upto 20%. In another embodiment, the poly(dimethylsiloxane) is dissolvedat a mass percent concentration up to 18%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration upto 16%. In another embodiment, the poly(dimethylsiloxane) is dissolvedat a mass percent concentration up to 14%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration upto 12%.

Purification

In one embodiment of the present invention, a method for purifyingpolyethylene includes contacting a contaminated polymer solution withsolid media at a temperature and at a pressure wherein the polymerremains dissolved in the fluid solvent. The solid media of the presentinvention, also referred to throughout the present invention asadsorption media or adsorption filtration media, comprise solid mediaparticles and are any solid materials that remove at least some of thecontamination from a solution of reclaimed polyethylene dissolved in thefluid solvent of the present invention. Although not wishing to be boundby any theory, the applicants believe that the solid media removecontamination by a variety of mechanisms. Non-limiting examples ofpossible mechanisms include adsorption, absorption, electrostatics, sizeexclusion, ion exclusion, ion exchange, and other mechanisms that may beapparent to those having ordinary skill in the art. Furthermore, thepigments and other contaminants commonly found in reclaimed polyethylenemay be polar compounds or may have polar compounds on their surfaces andmay preferentially interact with the solid media, which may also be atleast slightly polar. The polar-polar interactions are especiallyfavorable when non-polar solvents, such as alkanes, are used as thefluid solvent.

In one embodiment of the present invention, the solid media are selectedfrom the group consisting of inorganic substances, carbon-basedsubstances, or mixtures thereof. Useful examples of inorganic substancesinclude oxides of silicon, oxides of aluminum, oxides of iron, aluminumsilicates, magnesium silicates, amorphous volcanic glasses, silica,silica gel, diatomite, sand, quartz, reclaimed glass, alumina, perlite,fuller's earth, bentonite, and mixtures thereof. Useful examples ofcarbon-based substances include anthracite coal, carbon black, coke,activated carbon, cellulose, and mixtures thereof. In another embodimentof the present invention, the solid media are recycled glasses. In yetanother embodiment of the present invention, the solid media particlesare selected from the group consisting of solid particles of siliconoxide (silica), silica gel, aluminum oxide (alumina), activated alumina,iron oxide, aluminum silicate, magnesium silicate, sand, quartz,diatomaceous earth, zeolite, molecular sieve, perlite, clay, fuller'searth, bentonite clay, metal organic framework (MOF), covalent organicframework (COF), zeolitic imidazolate framework (ZIF), cellulose, andlignocellulose. In even yet another embodiment of the present invention,the solid media are selected from the group consisting of silica,activated alumina, silica gel, fuller's earth, bentonite clay, andmixtures thereof. In one embodiment of the present invention, the solidmedia are selected from the group consisting of activated carbon,activated alumina, diatomaceous earth, and mixtures thereof. In anotherembodiment of the present invention, the solid media are selected fromthe group consisting of MOF, COF, ZIF, activated carbon, activatedalumina, and mixtures thereof. In yet another embodiment of the presentinvention, the solid media are selected from the group consisting ofdiatomaceous earth, activated alumina, and mixtures thereof.

A non-limiting example of the physical mode of action is physicaladsorption (also called physisorption), where a dissolved contaminantgets adsorbed onto the external surface or internal surface of pores ofa filter particle due to van der Waals forces, and thus separated fromthe filtration feed stream. Another non-limiting example of the physicalmode of action is electrostatic adsorption, where a suspendedcontaminant gets adsorbed onto the surface of a filter particle due toelectrostatic attraction. The filter particles and media that removecontaminants primarily by adsorption are called adsorption filterparticles and adsorption filter media, respectively.

The adsorption filtration medium is typically contained in a cylindricalfilter container as either a loose medium or a bonded block, and theadsorption filtration can be either axial flow or radial flow. Thecylindrical adsorption filter medium in axial flow has an aspect ratiodefined as the ratio of the height to the diameter of the cylindricaladsorption filter medium. In one embodiment of the present invention,the aspect ratio of the cylindrical adsorption filter medium is equal toor greater than about 1. In another embodiment of the present invention,the aspect ratio of the cylindrical adsorption filter medium is equal toor greater than about 2. In yet another embodiment of the presentinvention, the aspect ratio of the cylindrical adsorption filter mediumis equal to or greater than about 5. In even yet another embodiment ofthe present invention, the aspect ratio of the cylindrical adsorptionfilter medium is equal to or greater than about 10. In one embodiment ofthe present invention, the aspect ratio of the cylindrical adsorptionfilter medium is equal to or greater than about 30. In anotherembodiment of the present invention, the aspect ratio of the cylindricaladsorption filter medium is equal to or greater than about 50. In yetanother embodiment of the present invention, the aspect ratio of thecylindrical adsorption filter medium is equal to or greater than about70.

In one embodiment of the present invention, the height of thecylindrical adsorption filter medium is equal to or greater than about 5cm. In another embodiment of the present invention, the height of thecylindrical adsorption filter medium is equal to or greater than about20 cm. In yet another embodiment of the present invention, the height ofthe cylindrical adsorption filter medium is equal to or greater thanabout 50 cm. In even yet another embodiment of the present invention,the height of the cylindrical adsorption filter medium is equal to orgreater than about 1 m. In one embodiment of the present invention, theheight of the cylindrical adsorption filter medium is equal to orgreater than about 1.5 m. In another embodiment of the presentinvention, the height of the cylindrical adsorption filter medium isequal to or greater than about 3 m. In yet another embodiment of thepresent invention, the height of the cylindrical adsorption filtermedium is equal to or greater than about 6 m.

In one embodiment of the present invention, the adsorption filter mediumis cylindrical; wherein the filter medium comprises loose adsorptionfilter particles; wherein the height of the cylindrical adsorptionmedium is about 122 cm; wherein the diameter of the cylindricaladsorption medium is about 1.7 cm; wherein the adsorption filterparticles comprise activated alumina; and wherein the particle size ofthe adsorption filter particles is 7×14 mesh.

In one embodiment of the present invention, the solid media arecontacted with the polymer in a vessel for a specified amount of timewhile the solid media are agitated. In another embodiment, the solidmedia are removed from the purer polymer solution via a solid-liquidseparation step. Non-limiting examples of solid-liquid separation stepsinclude filtration, decantation, centrifugation, and settling. Inanother embodiment of the present invention, the contaminated polymersolution is passed through a stationary bed of solid media. In anotherembodiment of the present invention, the solid media are replaced asneeded to maintain a desired purity of polymer. In yet anotherembodiment, the solid media are regenerated and re-used in thepurification step. In another embodiment, the solid media areregenerated by fluidizing the solid media during a backwashing step.

In one embodiment, a method for purifying reclaimed polymers includescontacting a polyethylene/fluid solvent solution with solid media at atemperature and at a pressure wherein the polyethylene remains dissolvedin the fluid solvent. In one embodiment, a method for purifyingreclaimed polymers includes contacting a polyethylene/fluid solventsolution with solid media at a temperature from about 90° C. to about280° C. In another embodiment, a method for purifying reclaimed polymersincludes contacting a polyethylene/fluid solvent solution with solidmedia at a temperature from about 110° C. to about 220° C. In oneembodiment, a method for purifying reclaimed polymers includescontacting a polyethylene/fluid solvent solution with solid media at apressure from about 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa).In another embodiment, a method for purifying reclaimed polymersincludes contacting a polyethylene/fluid solvent solution with solidmedia at a pressure from about 400 psig (2.76 MPa) to about 2,600 psig(17.93 MPa).

In one embodiment, a method for purifying reclaimed polymers includescontacting a polyethylene/n-butane solution with solid media at atemperature from about 90° C. to about 280° C. In another embodiment, amethod for purifying reclaimed polymers includes contacting apolyethylene/n-butane solution with solid media at a temperature fromabout 100° C. to about 220° C. In another embodiment, a method forpurifying reclaimed polymers includes contacting a polyethylene/n-butanesolution with solid media at a temperature from about 130° C. to about180° C. In another embodiment, a method for purifying reclaimed polymersincludes contacting a polyethylene/n-butane solution with solid media ata pressure from about 4000 psig (27.58 MPa) to about 8,000 psig (55.16MPa). In another embodiment, a method for purifying reclaimed polymersincludes contacting a polyethylene/n-butane solution with solid media ata pressure from about 4,200 psig (28.96 MPa) to about 7,000 psig (48.26MPa). In another embodiment, a method for purifying reclaimed polymersincludes contacting a polyethylene/n-butane solution with solid media ata pressure from about 4,500 psig (31.03 MPa) to about 6,000 psig (41.37MPa). In another embodiment, a method for purifying reclaimed polymersincludes contacting a polyethylene/n-butane solution with solid mediawherein the polyethylene is dissolved at a mass percent concentration ofat least 0.5%. In another embodiment, the polyethylene is dissolved at amass percent concentration of at least 1%. In another embodiment, thepolyethylene is dissolved at a mass percent concentration of at least2%. In another embodiment, the polyethylene is dissolved at a masspercent concentration of at least 3%. In another embodiment, thepolyethylene is dissolved at a mass percent concentration of at least4%. In another embodiment, the polyethylene is dissolved at a masspercent concentration of at least 5%. In another embodiment, a methodfor purifying reclaimed polymers includes contacting apolyethylene/n-butane solution with solid media wherein the polyethyleneis dissolved at a mass percent concentration up to 20%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration up to 18%. In another embodiment, the polyethylene isdissolved at a mass percent concentration up to 16%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration up to 14%. In another embodiment, the polyethylene isdissolved at a mass percent concentration up to 12%.

In another embodiment, a method for purifying reclaimed polymersincludes contacting a polyethylene/n-pentane solution with solid mediaat a temperature from about 90° C. to about 280° C. In anotherembodiment, a method for purifying reclaimed polymers includescontacting a polyethylene/n-pentane solution with solid media at atemperature from about 100° C. to about 220° C. In another embodiment, amethod for purifying reclaimed polymers includes contacting apolyethylene/n-pentane solution with solid media at a temperature fromabout 130° C. to about 180° C. In another embodiment, a method forpurifying reclaimed polymers includes contacting apolyethylene/n-pentane solution with solid media at a pressure fromabout 800 psig (5.52 MPa) to about 4,000 psig (27.58 MPa). In anotherembodiment, a method for purifying reclaimed polymers includescontacting a polyethylene/n-pentane solution with solid media at apressure from about 900 psig (6.21 MPa) to about 3,000 psig (20.68 MPa).In another embodiment, a method for purifying reclaimed polymersincludes contacting a polyethylene/n-pentane solution with solid mediaat a pressure from about psig (31.03 MPa) to about 6,000 psig (41.37MPa). In another embodiment, a method for purifying reclaimed polymersincludes contacting a polyethylene/n-pentane solution with solid mediawherein the polyethylene is dissolved at a mass percent concentration ofat least 0.5%. In another embodiment, the polyethylene is dissolved at amass percent concentration of at least 1%. In another embodiment, thepolyethylene is dissolved at a mass percent concentration of at least2%. In another embodiment, the polyethylene is dissolved at a masspercent concentration of at least 3%. In another embodiment, thepolyethylene is dissolved at a mass percent concentration of at least4%. In another embodiment, the polyethylene is dissolved at a masspercent concentration of at least 5%. In another embodiment, a methodfor purifying reclaimed polymers includes contacting apolyethylene/n-pentane solution with solid media wherein thepolyethylene is dissolved at a mass percent concentration up to 20%. Inanother embodiment, the polyethylene is dissolved at a mass percentconcentration up to 18%. In another embodiment, the polyethylene isdissolved at a mass percent concentration up to 16%. In anotherembodiment, the polyethylene is dissolved at a mass percentconcentration up to 14%. In another embodiment, the polyethylene isdissolved at a mass percent concentration up to 12%.

In one embodiment, a method for purifying reclaimed polymers includescontacting a polypropylene/n-butane solution with solid media at atemperature from about 90° C. to about 280° C. In another embodiment, amethod for purifying reclaimed polymers includes contacting apolypropylene/n-butane solution with solid media at a temperature fromabout 100° C. to about 220° C. In another embodiment, a method forpurifying reclaimed polymers includes contacting apolypropylene/n-butane solution with solid media at a temperature fromabout 130° C. to about 180° C. In another embodiment, a method forpurifying reclaimed polymers includes contacting apolypropylene/n-butane solution with solid media at a pressure fromabout 350 psig (2.41 MPa) to about 4,000 psig (27.57 MPa). In anotherembodiment, a method for purifying reclaimed polymers includescontacting a polypropylene/n-butane solution with solid media at apressure from about 1,000 psig (6.89 MPa) to about 3,500 psig (24.13MPa). In another embodiment, a method for purifying reclaimed polymersincludes contacting a polypropylene/n-butane solution with solid mediaat a pressure from about 2,000 psig (13.79 MPa) to about 3,000 psig(20.68 MPa). In another embodiment, a method for purifying reclaimedpolymers includes contacting a polypropylene/n-butane solution withsolid media wherein the polypropylene is dissolved at a mass percentconcentration of at least 0.5%. In another embodiment, the polypropyleneis dissolved at a mass percent concentration of at least 1%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration of at least 2%. In another embodiment, the polypropyleneis dissolved at a mass percent concentration of at least 3%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration of at least 4%. In another embodiment, the polypropyleneis dissolved at a mass percent concentration of at least 5%. In anotherembodiment, a method for purifying reclaimed polymers includescontacting a polypropylene/n-butane solution with solid media whereinthe polypropylene is dissolved at a mass percent concentration up to20%. In another embodiment, the polypropylene is dissolved at a masspercent concentration up to 18%. In another embodiment, thepolypropylene is dissolved at a mass percent concentration up to 16%. Inanother embodiment, the polypropylene is dissolved at a mass percentconcentration up to 14%. In another embodiment, the polypropylene isdissolved at a mass percent concentration up to 12%.

In another embodiment, a method for purifying reclaimed polymersincludes contacting a polypropylene/propane solution with solid media ata temperature from about 90° C. to about 280° C. In another embodiment,a method for purifying reclaimed polymers includes contacting apolypropylene/propane solution with solid media at a temperature fromabout 100° C. to about 220° C. In another embodiment, a method forpurifying reclaimed polymers includes contacting a polypropylene/propanesolution with solid media at a temperature from about 130° C. to about180° C. In another embodiment, a method for purifying reclaimed polymersincludes contacting a polypropylene/propane solution with solid media ata pressure from about 2,000 psig (13.79 MPa) to about 8,000 psig (55.16MPa). In another embodiment, a method for purifying reclaimed polymersincludes contacting a polypropylene/propane solution with solid media ata pressure from about 3,000 psig (20.68 MPa) to about 6,000 psig (41.37MPa). In another embodiment, a method for purifying reclaimed polymersincludes contacting a polypropylene/propane solution with solid media ata pressure from about 3,500 psig (24.13 MPa) to about 5,000 psig (34.47MPa). In another embodiment, a method for purifying reclaimed polymersincludes contacting a polypropylene/propane solution with solid mediawherein the polypropylene is dissolved at a mass percent concentrationof at least 0.5%. In another embodiment, the polypropylene is dissolvedat a mass percent concentration of at least 1%. In another embodiment,the polypropylene is dissolved at a mass percent concentration of atleast 2%. In another embodiment, the polypropylene is dissolved at amass percent concentration of at least 3%. In another embodiment, thepolypropylene is dissolved at a mass percent concentration of at least4%. In another embodiment, the polypropylene is dissolved at a masspercent concentration of at least 5%. In another embodiment, a methodfor purifying reclaimed polymers includes contacting apolypropylene/propane solution with solid media wherein thepolypropylene is dissolved at a mass percent concentration up to 20%. Inanother embodiment, the polypropylene is dissolved at a mass percentconcentration up to 18%. In another embodiment, the polypropylene isdissolved at a mass percent concentration up to 16%. In anotherembodiment, the polypropylene is dissolved at a mass percentconcentration up to 14%. In another embodiment, the polypropylene isdissolved at a mass percent concentration up to 12%.

In one embodiment, a method for purifying reclaimed polymers includescontacting a polystyrene/fluid solvent solution with solid media at atemperature and at a pressure wherein the polystyrene remains dissolvedin the fluid solvent. In another embodiment, a method for purifyingreclaimed polymers includes contacting a polystyrene/n-butane solutionwith solid media at a temperature from about 90° C. to about 280° C. Inanother embodiment, a method for purifying reclaimed polymers includescontacting a polystyrene/n-butane solution with solid media at atemperature from about 100° C. to about 220° C. In another embodiment, amethod for purifying reclaimed polymers includes contacting apolystyrene/n-butane solution with solid media at a temperature fromabout 130° C. to about 180° C. In another embodiment, a method forpurifying reclaimed polymers includes contacting a polystyrene/n-butanesolution with solid media at a pressure from about 1,000 psig (6.89 MPa)to about 9,000 psig (62.05 MPa). In another embodiment, a method forpurifying reclaimed polymers includes contacting a polystyrene/n-butanesolution with solid media at a pressure from about 2,000 psig (13.79MPa) to about 8,000 psig (55.16 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes contacting apolystyrene/n-butane solution with solid media at a pressure from about4,500 psig (31.03 MPa) to about 7,500 psig (51.71 MPa). In anotherembodiment, a method for purifying reclaimed polymers includescontacting a polystyrene/n-butane solution with solid media wherein thepolystyrene is dissolved at a mass percent concentration of at least0.5%. In another embodiment, the polystyrene is dissolved at a masspercent concentration of at least 1%. In another embodiment, thepolystyrene is dissolved at a mass percent concentration of at least 2%.In another embodiment, the polystyrene is dissolved at a mass percentconcentration of at least 3%. In another embodiment, the polystyrene isdissolved at a mass percent concentration of at least 4%. In anotherembodiment, the polystyrene is dissolved at a mass percent concentrationof at least 5%. In another embodiment, a method for purifying reclaimedpolymers includes contacting a polystyrene/n-butane solution with solidmedia wherein the polystyrene is dissolved at a mass percentconcentration up to 20%. In another embodiment, the polystyrene isdissolved at a mass percent concentration up to 18%. In anotherembodiment, the polystyrene is dissolved at a mass percent concentrationup to 16%. In another embodiment, the polystyrene is dissolved at a masspercent concentration up to 14%. In another embodiment, the polystyreneis dissolved at a mass percent concentration up to 12%.

In one embodiment, a method for purifying reclaimed polymers includescontacting a poly(dimethylsiloxane)/fluid solvent solution with solidmedia at a temperature and at a pressure wherein thepoly(dimethylsiloxane) remains dissolved in the fluid solvent. Inanother embodiment, a method for purifying reclaimed polymers includescontacting a poly(dimethylsiloxane)/n-butane solution with solid mediaat a temperature from about 115° C. to about 280° C. In anotherembodiment, a method for purifying reclaimed polymers includescontacting a poly(dimethylsiloxane)/n-butane solution with solid mediaat a temperature from about 120° C. to about 220° C. In anotherembodiment, a method for purifying reclaimed polymers includescontacting a poly(dimethylsiloxane)/n-butane solution with solid mediaat a temperature from about 140° C. to about 180° C. In anotherembodiment, a method for purifying reclaimed polymers includescontacting a poly(dimethylsiloxane)/n-butane solution with solid mediaat a pressure from about 500 psig (3.45 MPa) to about 2,100 psig (14.48MPa). In another embodiment, a method for purifying reclaimed polymersincludes contacting a poly(dimethylsiloxane)/n-butane solution withsolid media at a pressure from about 700 psig (4.83 MPa) to about 1,400psig (9.65 MPa). In another embodiment, a method for purifying reclaimedpolymers includes contacting a poly(dimethylsiloxane)/n-butane solutionwith solid media at a pressure from about 800 psig (5.52 MPa) to about1,300 psig (8.96 MPa). In another embodiment, a method for purifyingreclaimed polymers includes contacting a poly(dimethylsiloxane)/n-butanesolution with solid media wherein the poly(dimethylsiloxane) isdissolved at a mass percent concentration of at least 0.5%. In anotherembodiment, the poly(dimethylsiloxane) is dissolved at a mass percentconcentration of at least 1%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration ofat least 2%. In another embodiment, the poly(dimethylsiloxane) isdissolved at a mass percent concentration of at least 3%. In anotherembodiment, the poly(dimethylsiloxane) is dissolved at a mass percentconcentration of at least 4%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration ofat least 5%. In another embodiment, a method for purifying reclaimedpolymers includes contacting a poly(dimethylsiloxane)/n-butane solutionwith solid media wherein the poly(dimethylsiloxane) is dissolved at amass percent concentration up to 20%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration upto 18%. In another embodiment, the poly(dimethylsiloxane) is dissolvedat a mass percent concentration up to 16%. In another embodiment, thepoly(dimethylsiloxane) is dissolved at a mass percent concentration upto 14%. In another embodiment, the poly(dimethylsiloxane) is dissolvedat a mass percent concentration up to 12%.

Separation

In one embodiment of the present invention, a method for purifyingreclaimed polymers includes separating the purer polymer from the fluidsolvent at a temperature and at a pressure wherein the polymerprecipitates from solution and is no longer dissolved in the fluidsolvent. In another embodiment, the precipitation of the purer polymerfrom the fluid solvent is accomplished by reducing the pressure at afixed temperature. In another embodiment, the precipitation of the purerpolymer from the fluid solvent is accomplished by reducing thetemperature at a fixed pressure. In another embodiment, theprecipitation of the purer polymer from the fluid solvent isaccomplished by increasing the temperature at a fixed pressure. Inanother embodiment, the precipitation of the purer polymer from thefluid solvent is accomplished by reducing both the temperature andpressure. The solvent can be partially or completely converted from theliquid to the vapor phase by controlling the temperature and pressure.In another embodiment, the precipitated polymer is separated from thefluid solvent without completely converting the fluid solvent into a100% vapor phase by controlling the temperature and pressure of thesolvent during the separation step. The separation of the precipitatedpurer polymer is accomplished by any method of liquid-liquid orliquid-solid separation. Non-limiting examples of liquid-liquid orliquid-solid separations include filtration, decantation,centrifugation, and settling.

In one embodiment, a method for purifying reclaimed polymers includesseparating polyethylene from a polyethylene/fluid solvent solution at atemperature and a pressure wherein the polyethylene precipitates fromsolution. In another embodiment, a method for purifying reclaimedpolymers includes separating polyethylene from a polyethylene/n-butanesolution at a temperature from about 0° C. to about 280° C. In anotherembodiment, a method for purifying reclaimed polymers includesseparating polyethylene from a polyethylene/n-butane solution at atemperature from about 50° C. to about 175° C. In another embodiment, amethod for purifying reclaimed polymers includes separating polyethylenefrom a polyethylene/n-butane solution at a temperature from about 100°C. to about 220° C. In another embodiment, a method for purifyingreclaimed polymers includes separating polyethylene from apolyethylene/n-butane solution at a pressure from about 0 psig (0 MPa)to about 4,000 psig (27.58 MPa). In another embodiment, a method forpurifying reclaimed polymers includes separating polyethylene from apolyethylene/n-butane solution at a pressure from about 50 psig (0.34MPa) to about 2,000 psig (13.79 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes separating polyethylene from apolyethylene/n-butane solution at a pressure from about 75 psig (0.52MPa) to about 1,000 psig (6.89 MPa).

In another embodiment, a method for purifying reclaimed polymersincludes separating polyethylene from a polyethylene/n-pentane solutionat a temperature from about 0° C. to about 280° C. In anotherembodiment, a method for purifying reclaimed polymers includesseparating polyethylene from a polyethylene/n-pentane solution at atemperature from about 30° C. to about 150° C. In another embodiment, amethod for purifying reclaimed polymers includes separating polyethylenefrom a polyethylene/n-pentane solution at a temperature from about 50°C. to about 130° C. In another embodiment, a method for purifyingreclaimed polymers includes separating polyethylene from apolyethylene/n-pentane solution at a pressure from about 0 psig (0 MPa)to about 2,000 psig (13.79 MPa). In another embodiment, a method forpurifying reclaimed polymers includes separating polyethylene from apolyethylene/n-pentane solution at a pressure from about 50 psig (0.34MPa) to about 1,500 psig (10.34 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes separating polyethylene from apolyethylene/n-pentane solution at a pressure from about 75 psig (0.52MPa) to about 1,000 psig (6.89 MPa).

In one embodiment, a method for purifying reclaimed polymers includesseparating polypropylene from a polypropylene/fluid solvent solution ata temperature and at a pressure wherein the polypropylene precipitatesfrom solution. In another embodiment, a method for purifying reclaimedpolymers includes separating polypropylene from a polypropylene/n-butanesolution at a temperature from about 0° C. to about 220° C. In anotherembodiment, a method for purifying reclaimed polymers includesseparating polypropylene from a polypropylene/n-butane solution at atemperature from about 100° C. to about 200° C. In another embodiment, amethod for purifying reclaimed polymers includes separatingpolypropylene from a polypropylene/n-butane solution at a temperaturefrom about 130° C. to about 180° C. In another embodiment, a method forpurifying reclaimed polymers includes separating polypropylene from apolypropylene/n-butane solution at a pressure from about 0 psig (0 MPa)to about 2,000 psig (13.79 MPa). In another embodiment, a method forpurifying reclaimed polymers includes separating polypropylene from apolypropylene/n-butane solution at a pressure from about 50 psig (0.34MPa) to about 1,500 psig (10.34 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes separating polypropylene froma polypropylene/n-butane solution at a pressure from about 75 psig (0.52MPa) to about 1,000 psig (6.89 MPa).

In another embodiment, a method for purifying reclaimed polymersincludes separating polypropylene from a polypropylene/propane solutionat a temperature from about −42° C. to about 220° C. In anotherembodiment, a method for purifying reclaimed polymers includesseparating polypropylene from a polypropylene/propane solution at atemperature from about 0° C. to about 150° C. In another embodiment, amethod for purifying reclaimed polymers includes separatingpolypropylene from a polypropylene/propane solution at a temperaturefrom about 50° C. to about 130° C. In another embodiment, a method forpurifying reclaimed polymers includes separating polypropylene from apolypropylene/propane solution at a pressure from about 0 psig (0 MPa)to about 6,000 psig (41.37 MPa). In another embodiment, a method forpurifying reclaimed polymers includes separating polypropylene from apolypropylene/propane solution at a pressure from about 50 psig (0.34MPa) to about 3,000 psig (20.68 MPa). In another embodiment, a methodfor purifying reclaimed polymers includes separating polypropylene froma polypropylene/propane solution at a pressure from about 75 psig (0.52MPa) to about 1,000 psig (6.89 MPa).

In one embodiment, a method for purifying reclaimed polymers includesseparating polystyrene from a polystyrene/fluid solvent solution at atemperature and at a pressure wherein the polystyrene precipitates fromsolution. In another embodiment, a method for purifying reclaimedpolymers includes separating polystyrene from a polystyrene/n-butanesolution at a temperature from about 0° C. to about 220° C. In anotherembodiment, a method for purifying reclaimed polymers includesseparating polystyrene from a polystyrene/n-butane solution at atemperature from about 100° C. to about 200° C. In another embodiment, amethod for purifying reclaimed polymers includes separating polystyrenefrom a polystyrene/n-butane solution at a temperature from about 130° C.to about 180° C. In another embodiment, a method for purifying reclaimedpolymers includes separating polystyrene from a polystyrene/n-butanesolution at a pressure from about 0 psig (0 MPa) to about 2,000 psig(13.79 MPa). In another embodiment, a method for purifying reclaimedpolymers includes separating polystyrene from a polystyrene/n-butanesolution at a pressure from about 50 psig (0.34 MPa) to about 1,500 psig(10.34 MPa). In another embodiment, a method for purifying reclaimedpolymers includes separating polystyrene from a polystyrene/n-butanesolution at a pressure from about 75 psig (0.52 MPa) to about 1,000 psig(6.89 MPa).

In one embodiment, a method for purifying reclaimed polymers includesseparating poly(dimethylsiloxane) from a poly(dimethylsiloxane)/fluidsolvent solution at a temperature and at a pressure wherein thepoly(dimethylsiloxane) precipitates from solution. In anotherembodiment, a method for purifying reclaimed polymers includesseparating poly(dimethylsiloxane) from a poly(dimethylsiloxane)/n-butanesolution at a temperature from about 0° C. to about 220° C. In anotherembodiment, a method for purifying reclaimed polymers includesseparating poly(dimethylsiloxane) from a poly(dimethylsiloxane)/n-butanesolution at a temperature from about 115° C. to about 200° C. In anotherembodiment, a method for purifying reclaimed polymers includesseparating poly(dimethylsiloxane) from a poly(dimethylsiloxane)/n-butanesolution at a temperature from about 120° C. to about 180° C. In anotherembodiment, a method for purifying reclaimed polymers includesseparating poly(dimethylsiloxane) from a poly(dimethylsiloxane)/n-butanesolution at a pressure from about 0 psig (0 MPa) to about 1,500 psig(10.34 MPa). In another embodiment, a method for purifying reclaimedpolymers includes separating poly(dimethylsiloxane) from apoly(dimethylsiloxane)/n-butane solution at a pressure from about 50psig (0.34 MPa) to about 1,000 psig (6.89 MPa). In another embodiment, amethod for purifying reclaimed polymers includes separatingpoly(dimethylsiloxane) from a poly(dimethylsiloxane)/n-butane solutionat a pressure from about 75 psig (0.52 MPa) to about 500 psig (3.45MPa).

III Test Methods

The test methods described herein are used to measure the effectivenessof various methods for purifying polymers. Specifically, the methodsdescribed demonstrate the effectiveness of a given purification methodat improving color and translucency/clarity (i.e. making the color andopacity of the reclaimed polymer closer to that of an uncolored virginpolymer), reducing or eliminating elemental contamination (i.e. removingheavy metals), reducing or eliminating non-combustible contamination(i.e. inorganic fillers), reducing or eliminating volatile compounds(especially volatile compounds that contribute to the malodor ofreclaimed polymers), and reducing or eliminating polymeric contamination(i.e. polyethylene contamination in polypropylene).

Color and Opacity Measurement:

The color and opacity/translucency of a polymer are important parametersthat determine whether or not a polymer can achieve the desired visualaesthetics of an article manufactured from the polymer. Reclaimedpolymers, especially post-consumer derived reclaimed polymers, aretypically dark in color and opaque due to residual pigments, fillers,and other contamination. Thus, color and opacity measurements areimportant parameters in determining the effectiveness of a method forpurifying polymers.

Prior to color measurement, samples of either polymeric powders orpellets were compression molded into 30 mm wide×30 mm long×1 mm thicksquare test specimens (with rounded corners). Powder samples were firstdensified at room temperature (ca. 20-23° C.) by cold pressing thepowder into a sheet using clean, un-used aluminum foil as acontact-release layer between stainless steel platens. Approximately0.85 g of either cold-pressed powder or pellets was then pressed intotest specimens on a Carver Press Model C (Carver, Inc., Wabash, Ind.46992-0554 USA) pre-heated to 200° C. using aluminum platens, unusedaluminum foil release layers, and a stainless steel shim with a cavitycorresponding to aforementioned dimensions of the square test specimens.Samples were heated for 5 minutes prior to applying pressure. After 5minutes, the press was then compressed with at least 2 tons (1.81 metrictons) of hydraulic pressure for at least 5 seconds and then released.The molding stack was then removed and placed between two thick flatmetal heat sinks for cooling. The aluminum foil contact release layerswere then peeled from the sample and discarded. The flash around thesample on at least one side was peeled to the mold edge and then thesample was pushed through the form. Each test specimen was visuallyevaluated for voids/bubble defects and only samples with no defects inthe color measurement area (0.7″ (17.78 mm) diameter minimum) were usedfor color measurement.

The color of each sample was characterized using the InternationalCommission on Illumination (CIE) L*, a*, b* three dimensional colorspace. The dimension L* is a measure of the lightness of a sample, withL*=0 corresponding to the darkest black sample and L*=100 correspondingto the brightest white sample. The dimension a* is a measure of the redor green color of a sample with positive values of a* corresponding witha red color and negative values of a* corresponding with a green color.The dimension b* is a measure of the blue or yellow color of a samplewith positive values of b* corresponding with a yellow color andnegative values of b* corresponding with a blue color. The L*a*b* valuesof each 30 mm wide×30 mm long×1 mm thick square test specimen samplewere measured on a HunterLab model LabScan XE spectrophotometer (HunterAssociates Laboratory, Inc., Reston, Va. 20190-5280, USA). Thespectrophotometer was configured with D65 as the standard illuminant, anobserver angle of 10°, an area diameter view of 1.75″ (44.45 mm), and aport diameter of 0.7″ (17.78 mm).

The opacity of each sample, which is a measure of how much light passesthrough the sample (i.e. a measure of the sample's translucency), wasdetermined using the aforementioned HunterLab spectrophotometer usingthe contrast ratio opacity mode. Two measurements were made to determinethe opacity of each sample. One to measure the brightness value of thesample backed with a white backing, Y_(WhiteBacking), and one to measurethe brightness value of the sample backed with a black backing,Y_(BlackBacking). The opacity was then calculated from the brightnessvalues using the following Equation 3:

$\begin{matrix}{{\%\mspace{14mu}{Opacity}} = {\frac{Y_{{Black}\mspace{14mu}{Backing}}}{Y_{{White}\mspace{14mu}{Backing}}}*100}} & {{Equation}\mspace{14mu} 3}\end{matrix}$Elemental Analysis:

Many reclaimed polymers have unacceptably high concentrations of heavymetal contamination. The presence of heavy metals, for example lead,mercury, cadmium, and chromium, may prevent the use of reclaimedpolymers in certain applications, such as food or drug contactapplications or medical device applications. Thus, measuring theconcentration of heavy metals is important when determining theeffectiveness of a method for purifying polymers.

Elemental analysis was performed using Inductively Coupled Plasma MassSpectrometry (ICP-MS). Test solutions were prepared in n=2 to n=6depending on sample availability by combing ˜0.25 g sample with 4 mL ofconcentrated nitric acid and 1 mL of concentrated hydrofluoric acid(HF). The samples were digested using an Ultrawave Microwave Digestionprotocol consisting of a 20 min ramp to 125° C., a 10 min ramp to 250°C. and a 20 min hold at 250° C. Digested samples were cooled to roomtemperature. The digested samples were diluted to 50 mL after adding0.25 mL of 100 ppm Ge and Rh as the internal standard. In order toassess accuracy of measurement, pre-digestion spikes were prepared byspiking virgin polymer. Virgin polymer spiked samples were weighed outusing the same procedure mentioned above and spiked with the appropriateamount of each single element standard of interest, which included thefollowing: Na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd, and Pb. Spikes wereprepared at two different levels: a “low level spike” and a “high levelspike”. Each spike was prepared in triplicate. In addition to spikingvirgin polymer, a blank was also spiked to verify that no errorsoccurred during pipetting and to track recovery through the process. Theblank spiked samples were also prepared in triplicate at the twodifferent levels and were treated in the same way as the spiked virginpolymer and the test samples. A 9 point calibration curve was made bymaking 0.05, 0.1, 0.5, 1, 5, 10, 50, 100, and 500 ppb solutionscontaining Na, Al, Ca, Ti, Cr, Fe, Ni, Cu, Zn, Cd, and Pb. Allcalibration standards were prepared by dilution of neat standardreference solutions and 0.25 mL of 100 ppm Ge and Rh as the internalstandard with 4 mL of concentrated nitric and 1 mL of concentrated HF.Prepared standards, test samples, and spiked test samples were analyzedusing an Agilent's 8800 ICP-QQQMS, optimized according to manufacturerrecommendations. The monitored m/z for each analyte and the collisioncell gas that was used for analysis was as follows: Na, 23 m/z, H₂; Al,27 m/z, H₂; Ca, 40 m/z, H₂; Ti, 48 m/z, H₂; Cr, 52 m/z, He; Fe, 56 m/z,H₂; Ni, 60 m/z; no gas; Cu, 65 m/z, no gas; Zn, 64 m/z, He; Cd, 112 m/z;H₂; Pb, sum of 206≥206, 207≥207, 208≥208 m/z, no gas; Ge, 72 m/z, allmodes; Rh, 103 m/z, all modes. Ge was used as an internal standard forall elements <103 m/z and Rh was used for all elements >103 m/z.

Residual Ash Content:

Many reclaimed polymers contain various fillers, for example calciumcarbonate, talcum, and glass fiber. While useful in the originalapplication of the reclaimed polymer, these fillers alter the physicalproperties of a polymer in way that may be undesired for the nextapplication of the reclaimed polymer. Thus, measuring the amount offiller is important when determining the effectiveness of a method forpurifying polymers.

Thermogravimetric analysis (TGA) was performed to quantify the amount ofnon-combustible materials in the sample (also sometimes referred to asAsh Content). About 5-15 mg of sample was loaded onto a platinum samplepan and heated to 700° C. at a rate of 20° C./min in an air atmospherein a TA Instruments model Q500 TGA instrument. The sample was heldisothermal for 10 min at 700° C. The percentage residual mass wasmeasured at 700° C. after the isothermal hold.

Odor Analysis:

Odor sensory analysis was performed by placing about 3 g of each samplein a 20 mL glass vial and equilibrating the sample at room temperaturefor at least 30 min. After equilibration, each vial was opened and theheadspace was sniffed (bunny sniff) by a trained grader to determineodor intensity and descriptor profile. Odor intensity was gradedaccording to the following scale:

5=Very Strong

4=Strong

3=Moderate

2=Weak to Moderate

1=Weak

0=No odor

Polymeric Contamination Analysis:

Many reclaimed polymers, especially reclaimed polymers originating frommixed-stream sources, may contain undesired polymeric contamination.Without wishing to be bound by any theory, polymeric contamination, forexample polyethylene contamination in polypropylene, may influence thephysical properties of the polymer due to the presence of heterogeneousphases and the resulting weak interfaces. Furthermore, the polymericcontamination may also increase the opacity of the polymer and have aninfluence on the color. Thus, measuring the amount of polymericcontamination is important when determining the effectiveness of amethod for purifying polymers.

Semi-crystalline polymeric contamination was evaluated usingDifferential Scanning Calorimetry (DSC). For example, to measure theamount of polyethylene contamination in polypropylene, a set of fivepolypropylene/polyethylene blends were prepared with 2, 4, 6, 8, and 10wt % of Formolene® HB5502F HDPE (Formosa Plastics Corporation, USA) inPro-fax 6331 polypropylene (LyondellBasell Industries Holdings, B.V.).Approximately 5-15 mg of each sample was sealed in an aluminum DSC panand analyzed on a TA Instruments model Q2000 DSC with the followingmethod:

-   -   1. Equilibrate at 30.00° C.    -   2. Ramp 20.00° C./min to 200.00° C.    -   3. Mark end of cycle 0    -   4. Ramp 20.00° C./min to 30.00° C.    -   5. Mark end of cycle 1    -   6. Ramp 20.00° C./min to 200.00° C.    -   7. Mark end of cycle 2    -   8. Ramp 20.00° C./min to 30.00° C.    -   9. Mark end of cycle 3    -   10. Ramp 5.00° C./min to 200.00° C.    -   11. Mark end of cycle 4

The enthalpy of melting for the HDPE peak around 128° C. was calculatedfor each sample of known HDPE content using the 5.00° C./min DSCthermogram. A linear calibration curve, shown in FIG. 2, was establishedplotting enthalpy of melting versus known HDPE concentration (wt %).

Samples having unknown PE content were analyzed using the sameaforementioned DSC equipment and method. PE content was calculated usingthe aforementioned calibration curve. The specific HDPE used to generatethe calibration curve will more than likely have a different degree ofcrystallinity than the polyethylene (or polyethylene blend)contamination that may be present in a reclaimed polymer sample. Thedegree of crystallinity may independently influence the measuredenthalpy of melting for polyethylene and thus influence the resultingcalculation of polyethylene content. However, the DSC test methoddescribed herein is meant to serve as a relative metric to compare theeffectiveness of different methods to purify polymers and is not meantto be a rigorous quantification of the polyethylene content in a polymerblend. While the aforementioned method described the measurement ofpolyethylene contamination in polypropylene, this method may be appliedto measurement of other semi-crystalline polymers using differenttemperature ranges and peaks in the DSC thermogram. Furthermore,alternative methods, such as nuclear magnetic resonance (NMR)spectroscopy, may also be used to measure the amount of bothsemi-crystalline and amorphous polymeric contamination in a sample.

What is claimed is:
 1. A method for purifying a reclaimed polymercomprising: a. obtaining the reclaimed polymer wherein the reclaimedpolymer is selected from the group consisting of post-consumer usepolymers, post-industrial use polymers, and combinations thereof; b.contacting the reclaimed polymer at a temperature from about 80° C. toabout 280° C. and at a pressure from about 150 psig (1.03 MPa) to about8,000 psig (55.16 MPa) with a first fluid solvent having a standardboiling point less than about 70° C., to produce an extracted reclaimedpolymer; c. dissolving the extracted reclaimed polymer in a solventselected from the group consisting of the first fluid solvent, a secondfluid solvent, and mixtures thereof, at a temperature from about 90° C.to about 280° C. and a pressure from about 200 psig (1.38 MPa) to about9,000 psig (62.05 MPa) to produce a first solution comprising polymer,at least one dissolved contaminant, and at least one suspendedcontaminant; d. settling the first solution comprising polymer, at leastone dissolved contaminants, and at least one suspended contaminant at atemperature from about 90° C. to about 280° C. and at a pressure fromabout 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce asecond solution comprising polymer, at least one dissolved contaminant,and less of the at least one suspended contaminant; e. filtering thesecond solution at a temperature from about 90° C. to about 280° C. andat a pressure from about 200 psig (1.38 MPa) to about 9,000 psig (62.05MPa) to produce a third solution comprising purer polymer, at least onedissolved contaminant, and even less of the at least one suspendedcontaminant; and f. separating the purer polymer from the thirdsolution; and wherein the second fluid solvent has the same chemicalcomposition or a different chemical composition as the first fluidsolvent.
 2. The method of claim 1, wherein the purer polymer isseparated from the third solution at a temperature from about 0° C. toabout 280° C. and a pressure from about 0 psig (0 MPa) to 2,000 psig(13.79 MPa).
 3. The method of claim 1, wherein the reclaimed polymer isdissolved in the fluid solvent, or fluid solvent mixture, at a masspercent concentration of at least 0.5%.
 4. The method of claim 1,wherein the reclaimed polymer is post-consumer recycle derived polymer.5. The method of claim 1, wherein the reclaimed polymer is polystyrene.6. The method of claim 1, wherein the reclaimed polymer ispoly(dimethylsiloxane).
 7. The method of claim 1, wherein the reclaimedpolymer is a polypropylene homopolymer or a primarily polypropylenecopolymer.
 8. The method of claim 1, wherein the polymer is apolyethylene homopolymer or a primarily polyethylene copolymer.
 9. Themethod of claim 1, wherein the fluid solvent has a standard boilingpoint less than about 0° C. and greater than about −45° C. and astandard enthalpy change of vaporization of less than about +25 kJ/mol.10. The method of claim 1, wherein the fluid solvent is selected fromthe group consisting of olefinic hydrocarbons, aliphatic hydrocarbons,and mixtures thereof.
 11. The method of claim 1, wherein the aliphatichydrocarbon is selected from the group consisting of C₁-C₆ aliphatichydrocarbons and mixtures thereof.
 12. The method of claim 1, whereinthe aliphatic hydrocarbons and mixtures thereof is comprised ofprimarily C₄ aliphatic hydrocarbons.
 13. The method of claim 1, whereinthe fluid solvent comprises C₄ liquefied petroleum gas.
 14. The methodof claim 13, wherein the fluid solvent comprises n-butane, butaneisomers, or mixtures thereof.
 15. The method of claim 1, wherein thefluid solvent comprises n-pentane, isomers of pentane, or mixturesthereof.
 16. The method of claim 1, wherein the temperature in thecontacting, dissolving, settling and filtering steps is from about 110°C. to about 220° C.
 17. The method of claim 1, wherein the pressure inthe contacting step is from about 400 psig (2.76 MPa) to about 2,400psig (16.55 MPa).
 18. The method of claim 1, wherein the pressure in thecontacting step is less than about 1,100 psig (7.58 MPa).
 19. The methodof claim 1, wherein the pressure in the dissolving, settling, andfiltering steps is from about 400 psig (2.76 MPa) to about 2,600 (17.93MPa).
 20. A method for purifying a reclaimed polymer comprising: a.obtaining the reclaimed polymer wherein the reclaimed polymer isselected from the group consisting of post-consumer use polymers,post-industrial use polymers, and combinations thereof; b. contactingthe reclaimed polymer at a temperature from about 80° C. to about 280°C. and at a pressure from about 150 psig (1.03 MPa) to about 8,000 psig(55.16 MPa) with a first fluid solvent having a standard boiling pointless than about 70° C., to produce an extracted reclaimed polymer; c.dissolving the extracted reclaimed polymer in a solvent selected fromthe group consisting of the first fluid solvent, a second fluid solvent,and mixtures thereof, at a temperature from about 90° C. to about 280°C. and a pressure from about 200 psig (1.38 MPa) to about 9,000 psig(62.05 MPa) to produce a first solution comprising polymer, at least onedissolved contaminant, and at least one suspended contaminant; d.settling the first solution comprising polymer, at least one dissolvedcontaminants, and at least one suspended contaminant at a temperaturefrom about 90° C. to about 280° C. and at a pressure from about 200 psig(1.38 MPa) to about 9,000 psig (62.05 MPa) to produce a second solutioncomprising polymer, at least one dissolved contaminant, and less of theat least one suspended contaminant; e. filtering the second solution ata temperature from about 90° C. to about 280° C. and at a pressure fromabout 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) to produce athird solution comprising purer polymer, at least one dissolvedcontaminant, and even less of the at least one suspended contaminant;and f. purifying by further filtering the third solution at atemperature from about 90° C. to about 280° C. and at a pressure fromabout 200 psig (1.38 MPa) to about 9,000 psig (62.05 MPa) by contactingthe third solution with one or more solid media to produce a fourthsolution comprising purer polymer; and g. separating the purer polymerfrom the fourth solution; and wherein the second fluid solvent has thesame chemical composition or a different chemical composition as thefirst fluid solvent.